Bally Solved Lost World (Bally, 1978) blowing fuse

[LostWorld]

I'm a new member posting for the first time. The machine had been working just fine and then the other night I went to play it. I turned it on and immediately noticed a difference. It played it's start-up tune but I didn't hear the familiar sound that it makes (like one or more solenoids being energized). The ball wouldn't kick out so I put the ball in play by hand. The game "worked" but the only solenoids that work are the 2 flippers. A quick inspection revealed that the 1A. fuse on the underside of the playfield had blown. When placing the machine in the self test mode, the only solenoid that responds is the knocker. I shut it off, replaced the fuse and while looking at the fuse, I turned the machine back on. The normal "ping" sound, the lights blink, the tune plays and then the fuse lights up and melts. I called the guy who has worked on it before and described what is happening and he told me to buy a new solenoid driver board. Against my better judgement, I did and installed it and it makes no difference. I called him back (he lives 100 miles from me) and he had me install a 2 amp fuse (wasn't in favor of this) and turn the machine on for 15 seconds while feeling all solenoids for heat. None was found because.....the fuse blew. So, any thoughts/suggestions?

 

[LostWorld]

I just had the playfield upright looking for anything obvious. With no fuse in that location (playfield bottom) I turned on the machine, hit the credit button to "play" a game, touched some switches to accumulate some points and tapped the flipper buttons to activate them. While operating the flippers, I saw what I thought was some pretty big arcing of the contacts. I shut the machine off, took a new dollar bill and polished both sets, installed the 1 amp fuse, turned it back on and.........IT WORKS!!!!!!!!!
I'm going out to buy a lottery ticket.