Hey guys,
I've been bring an operation thunder back to life, and so far so good, except one drop target in a bank of 5 is not working. I cleaned all switches, put the game in test mode, and even manually closing the switch won't cause the game to recognize the switch closure. I tested the diode, visually inspected the wiring, and everything appears to be good. Is there anything else I can check that I might not be thinking of? It's just this one switch, as far as I can tell every other switch in the game works fine. Also, the game play is based around missions, and there is one mission that cannot be completed without the proper functioning of all drop targets. So basically every time this part of the game comes up, you will eventually lose your ball because the game won't recognize that you've completed it. please help!

Thanks guys! I'll report back when I have a chance to try those out.

UPDATE- Problem's been fixed. The wire that runs along the bottom and connects all the switches in the bank came loose on 2 of the switches. Just had to resolder. Very simple, and easily noticeable once we had removed the drop target bank from the machine.