This type of issue is almost certainly a single switch gap or a loose screw causing the issue on one component. Dont go crazy fixing things that are not broken and introduce new problems- resist the temptation to "just look around and fix anything that looks weird". I have caused myself issues doing this!

Dont have time to look now but schematic is the way forward! They are on IPDB and are FREE!

Schematics and manual suggest latch relay on game over relay as a probable cause.

Check to see if the latch relay works mechanically and watch to see if it engages. If it engages its probably the hold swith- if it does not you can look at stack 1a on score motor or reset relay or coin relay as they are in oath of latch.