Quoted from U2O3:My Williams machine is doing the same thing you described, question I have is what rivet and switch on the score reel are you referring to? I'm going to take another look at the score reel switch.
Rivet is a.reference to the player unit stepper which routs the score pulse to the reels. If you are having a similar issue where a score relay is locking with the playfield unplugged, check the player unit....it might be a dirty rivet, bent snowshoe, broken wire, or an alignment issue.