I made a few tests from the in game menus for a start. Especially did this to make sure the fricking head was working properly. It did, sort of.. only it turned the wrong way and the mouth coil did not work. I was thinking something had gone wrong when I reassembled the head but then I remembered I had switch the wires on the motor because I mounted it the wrong way. Not sure what the heck I was thinking about when I switched them but thats what I did. So, i switched them back and the head now turns the right way.
Still the mouth coil did not fire. I measured for voltage at the connector for it under the playfield but found none. Then I remembered.. the ball feeder coil was not soldered back so the circuit was broken there and hence the power did not reach the mouth coil. This has happened to me before on other projects so if you find something does not work when you reassemble a game remember to solder everything back before you dig too deep into it.
Another thing with the head unit that was very frustrating are the eye switches. They are a mess to line up properly because if they stick up too high (to get triggered by the ball) they will get in the way and get ripped by the turning head. I tried to replace the eye switches with the same kind of blade as is in the mouth switch but that did not work. Thats why there are different switch blades in the eyes and the mouth on this game. Might be possible to find a better way to do it for better precision but for now the original setup will do.
I can also mention if someone is having troubles with the head unit that the most common issues are the position switch not working properly (or its misaligned) or the head motor relay board which is located under the playfield. It tends to have its solder joints cracked so one thing to try is to reflow the solder joints on the board. I did that on mine while I hade it out even though it was working.
I reattached the coil wires and now the mouth coil did work again. Next I went into the head cycle test mode and the head does work pretty well now. But, sometimes when it turned the lower pop bumper would fire. Easily fixed by adjusting the bumper switch to less sensitivity.
Another thing I noticed when I turned on the game was that there were vibrations coming from the transformer.
Ive never noticed that before and I checked with some other games and its more than on those. My theory is that the vibrations spread out better in the cabinet since I glued the bottom to the rest of it. The original bottom was just slid into the guides in the cabinet sides.
Still, the vibrations are not super good. I think they are coming from some loose windings in the transformer. No biggie right now but with time more will probably break loose and they may even scratch of the coating on the wires causing a short. The fix for this would be to let some electric winding company tighten it up and rebake the transformer. Not sure what it costs but I will look into it.
Ive read somewhere that a bridge rectifier on the power board being put in in the wrong direction could also cause vibrations but im not sure about that one. Never the less I turned on the transformer with nothing connected whatsoever and the vibrations were still there.