Quoted from bigjimm64:First issue, the game locked up after draining the last ball in a game.
Most likely your power supply voltage is low, which causes the computer to freeze up.
Quoted from bigjimm64:At this time, the game kept playing as normal but the music stopped (the speech continued) and the scoring display was all garbled up. Next thing I know, the playfield is filling with smoke.
This time when the computer locked up, it turn on the right sling shot. Most likely you have a incorrect fuse in the game which did not burn quick enough so the coil melted.
Quoted from bigjimm64:point me in the right direction to figure this out.
You need a DMM, a soldering iron and some board repair experience.