1990 Williams Funhouse has a notorious problem of mysteriously
burning out a general illumination fuse for no apparent reason. This is
usually due to a coin chute lamp shorting against the lockdown bar lever.
Applying shrink-tubing or tape to the lever solves the problem.
A lesson to be learned from this is to note that some problems that exist
during play and go away while you have the machine apart, may not occur
because you have the machine apart!