When Thing takes the ball and drops it the game doesn't know where the ball went. It start looking for a missing ball. If the game is turned off and back on it gives a "missing ball" error. I checked continuity on switch 77 and it looked ok. Using the solenoid tests I expected Thing Kickout to fire and it did not.
What is supposed to happen when Thing hand drops the ball? Is the Thing Kickout supposed to fire right away or is the ball to sit on the switch? I read other posts about how to test Q68 if that is where this leads. Any suggestions on debugging this "Thing" would be appreciated.

When the ball hits the Thing kickout switch (77) what is supposed to happen?

LTG,
I suspected switch 77, Thing Kickout because that is when the game halts and starts looking for a ball. I did the switch edge test and had the ball roll over the switch and it closed as expected. I did the single switch test on it and was able to close/open it. So that seems like the actual switch is working.

Would the Thing Up Opto and Thing Down Opto cause the problem with the ball getting lost in the thing trough?

When the ball hits switch 77 is it supposed to be kicked out to the swamp immediately? I am thinking that if switch 77 checks out, the game expects the Thing kickout solenoid to fire and then one of the swamp lock switches should close. This leads me to guess that the solenoid not firing is the problem because the swamp lock switch does not close, not because the switch is bad but because the ball doesn't ever get sent there. Does this make sense?

I have to get a logic probe ordered up. Any suggestions on what to buy.
How do I trigger the solenoid? The only way I have been able to get it to fire was by grounding TIP102.

Just read TerryB's guide to Logic Probes and saw the suggested probe. Ordering it now.

Looking at the High Power Solenoid Circuit above I can identify the TIP36c as Q68. TIP 102 is Q67, and 2N5401 could be Q59 - Q62. I am guessing Q61 is the one for the circuit I need. Next is the LS374 which looks to be either U1 - U5, or U18. How do I determine which one and locate point A. This is the generic circuit shown in the TAF manual and I don't see any other more specific schematic.

zaza, thanks for the advice and I will try this today. You graphic explanations are first rate.

Some test results to report:
per zaza above
I ran the jumper from TP5 ground to the transistor side of R132 and the Solenoid 7 (Thing Kickout) DID fire indicating the transistors are good.
I tried the Solenoid 15 in solenoid test and it does NOT fire.

Since #15 did not fire what does this indicate?

My logic probe should be here Tuesday if you guys can suggest other testing.

Just so I understand the troubleshooting process could you explain the relationship between D6 and col/row 7? I do have the schematic and am curious as to the "why" as much as the what to do. I'll go check the lamps shortly.

I'll get into checking U5 once the probe arrives.

All of Col/Row 7 lamps were out. I reseated the ribbon and the lights and the Thing kickout both function now. zaza, you nailed it.

Do you guys do anything more permanent when ribbon cable reseating solves problem?

Thank you to everyone that chimed in on this thread. It was an interesting learning experience and I got to buy a logic probe for the next time.