Quoted from dr_nybble:

When they stick if you turn the machine off do they release? Then you can tell if it is a mechanical problem or not.

Quoted from currieddog:

I had that problem and it was a sticky plunger. Took it apart, cleaned with 91# rubbing alcohol, gave a light sanding with 600# paper, and all good.
It could also be that the two posts that go thru the playfield are catching on something.

Quoted from CNKay:

Coil stop looks funky, file it til it's flat and or rotate it 90°.
First dmm I ever saw with a separate ohm and volt jack. . What a pain in the ass that is.

Quoted from MarkG:

Stick how exactly? Are they getting power and pulling down or are they not getting power and are mechanically binding somehow? These would have very different solutions.

What are you trying to measure? These are AC coils so there's really no polarity. Either way, it seems unlikely that a bad coil is the problem unless the plunger is binding inside the coil.
/Mark

Quoted from zacaj:

If they hum while they're stuck then probably it's an electrical issue. I'd gap the switches (both eos and trigger) on each pop wider, and examine the switches on the pop relays

Quoted from YeOldPinPlayer:

Section 8.3: https://www.manualslib.com/manual/1113859/Sperry-Instruments-Dm-350a.html?page=6#manual
You'll need to know what coil you're measuring and what the resistance of that coil should be.
You'll find the information about what coil it should be on your schematics (or manual, if it has one) and you'll (probably) find the expected measurement at the link in post 2. If it's not there post what coil you have and someone will look it up for you.

Quoted from currieddog:

The plunger and the sleeve.

Quoted from jasonspoint28:

Road Race, cool theme! My Sky Jump has tandem pops. Each one has an end of stroke switch. When I got it, one switch was open so far it was obviously disabled. I did my best to gap them correctly, but that created a similar problem to yours-both would lock on. I opened one back up and viola, smooth poppin’ and no lockin’ ever since.

Quoted from MarkG:

Sounds like your coils are fine so you can probably put away the meter.
Each pop bumper has two switches mounted to it. The ball closes the top switch (closer to the playfield) that sends power to a relay that in turn sends power to the pop bumper solenoid. The other one (the End of Stroke or EOS switch) should open once the pop bumper reaches the bottom of its stroke, and cut power to the relay.
It could be that one of your EOS switches is shorted or isn't opening, or that one of the top switches is shorted or stuck closed.
For a better explanation, and to see how the pop bumper works in slow motion watch the video at:
https://www.funwithpinball.com/exhibits/small-boards#PopBumpers

Quoted from zacaj:

That switch needs to open fully when the pop bumper is energized, or it'll stay locked on.

Quoted from MarkG:

Sounds like your coils are fine so you can probably put away the meter.
Each pop bumper has two switches mounted to it. The ball closes the top switch (closer to the playfield) that sends power to a relay that in turn sends power to the pop bumper solenoid. The other one (the End of Stroke or EOS switch) should open once the pop bumper reaches the bottom of its stroke, and cut power to the relay.
It could be that one of your EOS switches is shorted or isn't opening, or that one of the top switches is shorted or stuck closed.
For a better explanation, and to see how the pop bumper works in slow motion watch the video at:
https://www.funwithpinball.com/exhibits/small-boards#PopBumpersthe switches all look like they are gapped just fine like in the bumper video. If there is a short of some kind how would I check or repair it?

Quoted from newmantjn:

1. Mechanical Binding
- Plunger/sleeve
- Platter/pop body
- Platter/Spoon switch
2. Plunger coil stop
3. EOS switch Adjustment
4. Control Relay
- Binding
- Magnetized armature
- Switch Adjustment
My money is on 4 - magnetized armature, since I think you have more or less covered everything else except the platter and you probably would have noticed that.

Quoted from newmantjn:

1. Mechanical Binding
- Plunger/sleeve
- Platter/pop body
- Platter/Spoon switch
2. Plunger coil stop
3. EOS switch Adjustment
4. Control Relay
- Binding
- Magnetized armature
- Switch Adjustment
My money is on 4 - magnetized armature, since I think you have more or less covered everything else except the platter and you probably would have noticed that.

Quoted from frunch:

What i did for the magnetized pop bumper assemblies on my Black Hole:
Layer a couple small pieces of scotch tape on the surface of the coil stop where the plunger makes contact. Made a world of difference in the performance on my game-no more sticking pops. There's probably better/cleaner solutions, but it's done great for my BH so far. I even went ahead and did it on the pops i wasn't really having trouble with and i swear they also work a little snappier in result.
Hopefully that helps if you're still dealing with magnetized plunger/stop, which may be possible...
Also, as zacaj asked earlier, does the coil continue to hum after it's activated and stuck? Or is it quiet, but will only release if you manually pull it up?

Quoted from frunch:

Ahhh, forget about magnetized stops/plungers for now--i overlooked part of the thread that pretty much addressed that.
Well if it's continuing to hum, it may not be opening the end of stroke switch as zacaj was mentioning earlier. With the game off and the playfield opened up, move the pop bumper rod and ring up and down manually, you should see a switch on the pop bumper mech open as the rod and ring is pulling into the coil and closing as it springs back to its resting state. Sometimes a leaf from that switch can get on the wrong side of the pop bumper yoke that activates it.
If the switches are adjusted properly, next thing to check would be whichever relay activates the pop bumpers. There may be a switch on that relay that needs adjustment. Not sure which relay that would be, but you should be able to find it on the schematic.

Quoted from jasonspoint28:

Curious that a flipper button will unstick it. Wish I had the schematics.

Quoted from dr_nybble:

Did you report yet what happens when you turn the machine off when it is sticking?

Quoted from YeOldPinPlayer:

You won't find them online. Unlike every other manufacturer, Gottlieb claims copyright on their schematics. This means generally it's harder to get assistance with them because almost no one has documentation.
You can buy a copy from http://pbresource.com/mansch.html

Quoted from MarkG:

Here is the pop bumper arrangement from Mibs, made just a few months before Road Race. It's the same basic arrangement for most games I suspect. Your wire colors will be different but the basic operation should be the same.
[quoted image]
The two normally open spoon switches in the upper right corner are the spoon shaped switches just below the playfield on two different pop bumpers. When the ball tips the pop bumper skirt on either pop bumper the spoon switch closes and sends power to the pop bumper relay (the H relay in this game) which activates the pop bumper relay.
When the H/Pop Bumper relay activates it closes its own normally open lock in switch to keep itself active (or locked in) after the ball rolls away and the spoon switch opens.
At the same time the H/Pop Bumper relay closes two other switches that send power to the pop bumper solenoids. These switches will have larger, high current contacts on them so they'll look a little different than the lock in switch which will have smaller, lower current contacts.
With the H/Pop Bumper relay active and power going to the two pop bumpers, the pop bumper rings pull down and should eventually open the two EOS switches mounted below the spoon switches. Once both EOS switches open the lock in circuit is broken and power is cut to the H/Pop Bumper relay.
When the H/Pop Bumper relay relaxes the two switches sending power to the pop bumpers open to cut power to the pop bumpers.
It sounds as though your H relay switches (at the bottom of the schematic) aren't opening. So either the H/Pop Bumper relay isn't relaxing or the H relay switches are gapped too close.
The pop bumper relay is usually mounted under the playfield near the pop bumpers it controls. You should see it fire any time a pop bumper fires. Shut the power off and manually operate the pop bumpers and the pop bumper relay and see if every switch opens or closes as the device activates and relaxes.thank you so much for this I will get back to you with the results as soon as I get time to look. Thanks again

Quoted from oldpins:

As MarkG has thoroughly explained, have a look at link to an animation I made a few years back. While the circuit wiring will differ to your title, same principles apply. Sometimes pictures can help.

Quoted from MarkG:

Here is the pop bumper arrangement from Mibs, made just a few months before Road Race. It's the same basic arrangement for most games I suspect. Your wire colors will be different but the basic operation should be the same.
[quoted image]
The two normally open spoon switches in the upper right corner are the spoon shaped switches just below the playfield on two different pop bumpers. When the ball tips the pop bumper skirt on either pop bumper the spoon switch closes and sends power to the pop bumper relay (the H relay in this game) which activates the pop bumper relay.
When the H/Pop Bumper relay activates it closes its own normally open lock in switch to keep itself active (or locked in) after the ball rolls away and the spoon switch opens.
At the same time the H/Pop Bumper relay closes two other switches that send power to the pop bumper solenoids. These switches will have larger, high current contacts on them so they'll look a little different than the lock in switch which will have smaller, lower current contacts.
With the H/Pop Bumper relay active and power going to the two pop bumpers, the pop bumper rings pull down and should eventually open the two EOS switches mounted below the spoon switches. Once both EOS switches open the lock in circuit is broken and power is cut to the H/Pop Bumper relay.
When the H/Pop Bumper relay relaxes the two switches sending power to the pop bumpers open to cut power to the pop bumpers.
It sounds as though your H relay switches (at the bottom of the schematic) aren't opening. So either the H/Pop Bumper relay isn't relaxing or the H relay switches are gapped too close.
The pop bumper relay is usually mounted under the playfield near the pop bumpers it controls. You should see it fire any time a pop bumper fires. Shut the power off and manually operate the pop bumpers and the pop bumper relay and see if every switch opens or closes as the device activates and relaxes.

Quoted from MarkG:

Here is the pop bumper arrangement from Mibs, made just a few months before Road Race. It's the same basic arrangement for most games I suspect. Your wire colors will be different but the basic operation should be the same.
[quoted image]
The two normally open spoon switches in the upper right corner are the spoon shaped switches just below the playfield on two different pop bumpers. When the ball tips the pop bumper skirt on either pop bumper the spoon switch closes and sends power to the pop bumper relay (the H relay in this game) which activates the pop bumper relay.
When the H/Pop Bumper relay activates it closes its own normally open lock in switch to keep itself active (or locked in) after the ball rolls away and the spoon switch opens.
At the same time the H/Pop Bumper relay closes two other switches that send power to the pop bumper solenoids. These switches will have larger, high current contacts on them so they'll look a little different than the lock in switch which will have smaller, lower current contacts.
With the H/Pop Bumper relay active and power going to the two pop bumpers, the pop bumper rings pull down and should eventually open the two EOS switches mounted below the spoon switches. Once both EOS switches open the lock in circuit is broken and power is cut to the H/Pop Bumper relay.
When the H/Pop Bumper relay relaxes the two switches sending power to the pop bumpers open to cut power to the pop bumpers.
It sounds as though your H relay switches (at the bottom of the schematic) aren't opening. So either the H/Pop Bumper relay isn't relaxing or the H relay switches are gapped too close.
The pop bumper relay is usually mounted under the playfield near the pop bumpers it controls. You should see it fire any time a pop bumper fires. Shut the power off and manually operate the pop bumpers and the pop bumper relay and see if every switch opens or closes as the device activates and relaxes.

Quoted from MarkG:

Here is the pop bumper arrangement from Mibs, made just a few months before Road Race. It's the same basic arrangement for most games I suspect. Your wire colors will be different but the basic operation should be the same.
[quoted image]
The two normally open spoon switches in the upper right corner are the spoon shaped switches just below the playfield on two different pop bumpers. When the ball tips the pop bumper skirt on either pop bumper the spoon switch closes and sends power to the pop bumper relay (the H relay in this game) which activates the pop bumper relay.
When the H/Pop Bumper relay activates it closes its own normally open lock in switch to keep itself active (or locked in) after the ball rolls away and the spoon switch opens.
At the same time the H/Pop Bumper relay closes two other switches that send power to the pop bumper solenoids. These switches will have larger, high current contacts on them so they'll look a little different than the lock in switch which will have smaller, lower current contacts.
With the H/Pop Bumper relay active and power going to the two pop bumpers, the pop bumper rings pull down and should eventually open the two EOS switches mounted below the spoon switches. Once both EOS switches open the lock in circuit is broken and power is cut to the H/Pop Bumper relay.
When the H/Pop Bumper relay relaxes the two switches sending power to the pop bumpers open to cut power to the pop bumpers.
It sounds as though your H relay switches (at the bottom of the schematic) aren't opening. So either the H/Pop Bumper relay isn't relaxing or the H relay switches are gapped too close.
The pop bumper relay is usually mounted under the playfield near the pop bumpers it controls. You should see it fire any time a pop bumper fires. Shut the power off and manually operate the pop bumpers and the pop bumper relay and see if every switch opens or closes as the device activates and relaxes.

Quoted from MarkG:

Here is the pop bumper arrangement from Mibs, made just a few months before Road Race. It's the same basic arrangement for most games I suspect. Your wire colors will be different but the basic operation should be the same.
[quoted image]
The two normally open spoon switches in the upper right corner are the spoon shaped switches just below the playfield on two different pop bumpers. When the ball tips the pop bumper skirt on either pop bumper the spoon switch closes and sends power to the pop bumper relay (the H relay in this game) which activates the pop bumper relay.
When the H/Pop Bumper relay activates it closes its own normally open lock in switch to keep itself active (or locked in) after the ball rolls away and the spoon switch opens.
At the same time the H/Pop Bumper relay closes two other switches that send power to the pop bumper solenoids. These switches will have larger, high current contacts on them so they'll look a little different than the lock in switch which will have smaller, lower current contacts.
With the H/Pop Bumper relay active and power going to the two pop bumpers, the pop bumper rings pull down and should eventually open the two EOS switches mounted below the spoon switches. Once both EOS switches open the lock in circuit is broken and power is cut to the H/Pop Bumper relay.
When the H/Pop Bumper relay relaxes the two switches sending power to the pop bumpers open to cut power to the pop bumpers.
It sounds as though your H relay switches (at the bottom of the schematic) aren't opening. So either the H/Pop Bumper relay isn't relaxing or the H relay switches are gapped too close.
The pop bumper relay is usually mounted under the playfield near the pop bumpers it controls. You should see it fire any time a pop bumper fires. Shut the power off and manually operate the pop bumpers and the pop bumper relay and see if every switch opens or closes as the device activates and relaxes.

Quoted from MarkG:

Here is the pop bumper arrangement from Mibs, made just a few months before Road Race. It's the same basic arrangement for most games I suspect. Your wire colors will be different but the basic operation should be the same.
[quoted image]
The two normally open spoon switches in the upper right corner are the spoon shaped switches just below the playfield on two different pop bumpers. When the ball tips the pop bumper skirt on either pop bumper the spoon switch closes and sends power to the pop bumper relay (the H relay in this game) which activates the pop bumper relay.
When the H/Pop Bumper relay activates it closes its own normally open lock in switch to keep itself active (or locked in) after the ball rolls away and the spoon switch opens.
At the same time the H/Pop Bumper relay closes two other switches that send power to the pop bumper solenoids. These switches will have larger, high current contacts on them so they'll look a little different than the lock in switch which will have smaller, lower current contacts.
With the H/Pop Bumper relay active and power going to the two pop bumpers, the pop bumper rings pull down and should eventually open the two EOS switches mounted below the spoon switches. Once both EOS switches open the lock in circuit is broken and power is cut to the H/Pop Bumper relay.
When the H/Pop Bumper relay relaxes the two switches sending power to the pop bumpers open to cut power to the pop bumpers.
It sounds as though your H relay switches (at the bottom of the schematic) aren't opening. So either the H/Pop Bumper relay isn't relaxing or the H relay switches are gapped too close.
The pop bumper relay is usually mounted under the playfield near the pop bumpers it controls. You should see it fire any time a pop bumper fires. Shut the power off and manually operate the pop bumpers and the pop bumper relay and see if every switch opens or closes as the device activates and relaxes.