I am having issues bringing a Whirlwind back from the dead after years in storage. It now has a new Rottendog MPU in it and is booting up and playing normally. However, the upper right flipper does not work.
Initially I noticed the bottom flippers were weak. Only the hold winding of the coils were working. This was due to corrosion on the EOS switches which meant they were always open. I replaced the EOS switches and then the bottom flippers started working normally. I was expecting the same issue on the upper flipper but it doesn't seem to be it. I used a clip to short the EOS switch and the flipper still does not work. No action at all. I have 75v at each of the coil lugs. I thought the issue was the coil, but I replaced the coil and diodes and still have the same problem. Fuses are OK. When I ground the non-banded side of the coil with a jumper wire, the coil does activate, but only very weakly. It's not even strong enough to fully pull the plunger in. The flipper plunger and crank move freely by hand so it is not a binding issue.
I have absolutely no idea where to go from here. Grounding the coil manually should always produce a full force flip, yet I only get a very weak one, and not even a full flip at that. However the coil was replaced and there was no change in behaviour. I verified wiring was correct on the coil lugs.
Where should I go from here?