Quoted from DGMartin:Here is something you could try to isolate the problem. On the left side of the GI fuse there are a bundle of GI wires soldered to the fuse bracket. Unsolder the whole bunch and then with the power on and a new fuse installed, touch each wire to the fuse holder and see what lights up. The area with the short won't light up and will blow the fuse if you hold it there very long. That way you'll know the general area where the short is and this will help you find it. My guess is that possibly a screw touched a wire and grounded it or you have a shorted light socket. This method will help you isolate where the problem is. Best I can think of.
Ok here’s what is going on with my GI fuse blowing. I unsoldered all the wires and isolated which one was blowing the fuse. It’s the yellow wire for the play field GI.
I soldered just that wire back to the fuse and I Pulled all the lights out with the playfield propped up resting where the lock down bar goes. Put one light in at a time and all the GI lights worked and fuse didn’t blow.
When I go to put the playfield down near to the resting and locked in position, it starts to short the GI fuse and lights go out. I raise it up and it’s ok. So at this point not sure what it’s coming in contact with to cause it to short out. Can’t see any wires being pinched or anything obvious.
Got the magnet to work and the GOR drop target. Only thing I did prior to 20 amp GI fuse blowing was to screw the C upper play field roll over light socket to the play field.