Quoted from Marcus:
Yes I also think a bad connection. But I measured J5 pin 15, that goes to left sling coil and that measures fine but wont work when slingshot switches are closed. Which connection on solenoid board receives signal from mpu board? Could that be the connection/pin that is bad?
(I am a bit into replacing U2 and maybe U1 just to see if that is the problem, or is that overdoing it and unnessesary?)
Lower right .100 connector receives the signals from the MPU board. You'd probably see some other solenoid issues if one of those pins were bad unless that one sling happens to be the only one on the topmost signal.
No reason at all to replace U1 it has nothing to do with your sling circuit. Get a logic probe and start measuring pulses in solenoid test to determine where your signal is getting lost. A good test is the input of U3 and the output of U3, specifically pin 8 for the input and pin 7 for the output. You should get a negative pulse when the solenoid test passes the sling.
Was the star trek machine the same exact connector and connection for the sling? If it wasn't.... that test didn't tell you anything, really.
I agree with the other posters it's probably a cracked header pin or a damaged connector in your Kiss harness.