You have a short somewhere in that playfield light circuit. They can be kind of tedious to find unless you get lucky. Look very closely at every light socket and see if you can spot anything wrong - look for 2 metal pieces touching where they shouldn't be, insulation missing off wire somewhere, wires pinched really tightly..anything where metal is touching metal.
As HowardR mentioned, a 10A circuit breaker soldered to a fuse that you can just plug in will save you lots of fuses! I know most people don't just have those lying around, but if you feel like investing 20 bucks, they're very valuable for chasing down shorts without going through a million fuses:
amazon.com link »
I got lucky using a resettable circuit breaker one time, which took about 3 or 4 seconds to blow after the power went on. I put the breaker in, turned off the room lights, and then turned power on to the machine. I was able to see a small, bright glow under the playfield just before the breaker blew - pointed me right to the short. Might be worth a try, though a normal fuse might blow too fast for that to work. I think you'll just have to be patient and observant and track it down visually unless someone else out there has a better idea.
Who knows what that hack wire was supposed to do - if it was hooked to the motor 1A, then it wouldn't have anything to do with lights. I wouldn't worry about it for now.