Finalizing plunger cleaning with Lemon Pledge can be a plus..
Also, Ballys maybe somewhat, but United/Williams insulating spacers
seem to have had more ability to shrink. Snugging up the switch stack
screws before adjusting is always a plus..
Lubing wasn't always a priority to many of the old time vendors.
Many things function off of the Score Motor's wiper board. Checking the
Score Motor's wiper finger rivets for extreme excessive ware is always a
good policy..

Frankfort's just east of Utica. I don't remember before knowing that..
Anyways, you have the Williams football (forgot the name) P&B?
I never had that machine, and I'm sure you checked the lights'
corresponding relays, so maybe it has a source that it's back feeding
from. Without the schematics, it's tough to have an idea, but if I had
to take a shot, I'd go with a make/break switch.
I recently had a very strange experience with a make/break on a Cowpoke.
I'm still somewhat scratching my head. Had to finesse to solve the problem..

That's right. Gridiron. I played one years back..
I'm sure you had already carefully checked the front, but perhaps the backside of the Football
Unit's wiper board. Probably not, but maybe a foreign wire stran..