As Boots suggests - could be the fuse holder. Might also be the EMI filter. At least you know it is the machine !
What Nino said.
This is mains and THE MOST DANGEROUS part of the machine - please get it right.
The fuse holders used in most pinballs would never pass Australian standards and should be replaced. One "feature" of some of them is the way they can be wired so that the exposed terminal (when the fuse holder is removed) is LIVE - idiotic design full stop! Think carefully when wiring up a replacement to ensure the "hot" end of the holder is not exposed when the fuse is removed.
The EMI filters are also 20 +++ years old and a lot are starting to "leak" electrically between terminals and ground. For $10 from Jaycar it just isn't worth the risk.
Under $20 gets your fuse holder & fuse, EMI filter and MOV & Thermistor (where fitted in applicable machines) replaced so that is my suggestion for the very first thing that should be done to ANY and EVERY pinball coming into Australia aside from replacing the mains lead and plug itself of course.
