Tonight, the Pinball Gods looked upon me...
... they saw I'd been struggling for some time, and saw I was finally nearing the top of the hill...
...so they pointed, laughed, and smote me.
Here's how it went down.
We left off planning to take a look at the O relay. I removed the spring. There was still a little resistance from the switches (but less overall), so I didn't even bother putting another spring on there. I started up the machine and manually closed the O relay.
--> O relay held closed with significantly less (but still a little) buzzing.
Next, I closed the outhole switch, to see if the game would behave differently. It didn't.
--> Game still stepped through all five balls without stopping.
On a whim, I removed the spring from P too, but that didn't make any difference either.
I decided to take a look at switches on the back of the ball stepper. (Reference my earlier musings about perhaps the ball stepper not "telling" the machine it's moved to the next ball.) I removed the screw from the top of the stepper mounting plate and swung it down. It has three switches back there:
1) Switch with red/green on one lug and red/black on the other; switch is closed until after 5th ball when cam lever opens it. (Note: Red/green appears on AB relay; red/black appears on hold relay R.)
2) Switch with orange/red & orange/white on one lug, and the other lug has a jumper to the red/green wire (on switch 1); switch is open on zero position, closed on balls 1-5 & 6th position.
3) Switch with thin blue on one lug and thin green on the other; switch is open on zero position, closed on balls 1-5 & 6th position.
--> I checked resistance and Switches 1 & 2 were normal.
--> Strangely, Switch 3 still showed 0 resistance when open.
I investigated the Switch 3 condition further by tracing the wires ... it appears the green wire runs up to a terminal shared by the orange/black wire coming off the outhole switch. The green wire also appears to go to one of the Q relay's coil lugs. The blue wires appear to go to the vari-targets' coils.
Seeing the red-green wire coming off switch 1, and figuring it was probably related to the red-green at the AB relay, I decided to see what would happen without this switch closed. I separated the switch leaves with a q-tip shaft, and started the game -- but nothing happened when I closed the outhole switch. Hmm. Ok.
I took the q-tip out, tried again -- but now still nothing happens with the outhole switch closed. WTH?
Mildly panicked, I put everything back the way it was before I even started messing with anything tonight. Still nothing with the outhole switch closed! WTF!!!
After startup, I know the Q relay should pull in when you close the outhole switch. I can manually try to cycle Q, but nothing happens. Also, now if I manually cycle O, nothing happens either. Motor still turns when I cycle P. I hit the O & Q relays with a 9V battery, they still pull in.
Hope you've had a good laugh, Pinball Gods. You won't relish in my misery any more tonight, I'm going to bed. Will try to approach it fresh at the next opportunity, hopefully with some advice from my pals fred & woz -- who have more than earned a few beers after all this is over.