Did a bit of work with it today.

BTTF doesnt use EOS switches, found a blown fuse on the PPB Board. Replaced the fuse but the second you start a game the VUK and knocker activate and stay on causing the fuse to blow again. If I disconnect both coils and the system will be fine, both flippers work at 100%, checked both coils which are fine but if  I connect either one back up then I have the same problem.

Anyone else come across this problem??   

Cheers Mark.