First we need to figure out if it is a switch problem or solenoid problem. When it misfires, does it still score points?

treat this like a switch issue then. The computer reads the switch is closed and then the computer tells the solenoid to pop. Since you have no scoring, the computer isn't seeing that this switch is getting closed.

Start simple. Check the switch itself. Clean it by wiping the contacts with a business card. You can also try this... with the game off. Attach your DMM set to beep when continuity on the switch blades. Close the switch and listen for it to beep. If it is not consistent, you can try cleaning or just replace it.

Don't use the "tone". Some meters will trigger the tone as high as 300 ohms. You need to watch the actual reading on the meter and see what it does. It should almost be a dead short (just like you touching the leads together). Then, you should move the switch while closed (closed, more closed, less closed) and see if the number rise a large amount while you move the points. This would indicate an unclean surface on the contacts. If it holds with a solid low ohms reading (like under 1 or 2 ohms) then you have a switch making good contact.

Some new switches can already be tarnished. As stated, clean with the wipe of a business card. If you used a flex stone or file on your new switch, you basically destroyed it since you would have scared the gold flashing on them.

Check that cap.

It's job is to make sure the CPU does not miss any hits; so if it's dead, you will not get consistent response.

At your leasure, get a bunch of those 50v .05uf caps.

They fail ALL THE TIME in the Classic Bally games. Often shorting the switch ON, or flicking ON/OFF/ON .

If I'm doing a playfield swap, I replace them all (just about every playfield switch has one).

100 of them for .90 cents:

http://www.taydaelectronics.com/capacitors/ceramic-disc-capacitors/10-x-0-047uf-50v-ceramic-disc-capacitor-pkg-of-10.html

Can I use a higher voltage cap in lieu of the 50V?

I'm doing a playfield swap on a power play (that's how I found this thread re: caps) Several caps didn't handle the transition too well. I have .05uF 600V caps I use when re-capping my tube radios- I'm fairly certain I can- just looking for confirmation.
thanks!

If the higher voltage capacitor fits, then you should be OK to use it.

Just an aside, I had another issue with the caps under the playfield - the leads were long, and a cap lead got into the GI circuitry. Wasn't very pretty. Make sure the lead from the cap can't be pushed into the GI braiding. If in doubt, use a piece of electrical tape over the GI braid to insulate it from the capacitor lead.

Ended up going to radio shack near me and getting all their .047 50v capacitors. The 600v were a little large the left is 600v the right 50v.

IMG_1438 (resized).JPG

I did see what you meant with the caps sitting near the gi line. I'll be using a brush on insulator where things get close. Thanks for the tip!