Sorry, Boatcat, I do read your posts to others and envy your immense knowledge and how you patiently share it with others. So I feel real bad that I have been away from the forum for a while and missed your helpful advice. Please forgive!
You seem to be spot on re the reset relay (which for some reason I called the KB when it is in fact the DB relay) it seems real touchy. On inspection it seems all okay (1B, 5A iirc), but I suspect there is some unwanted movement or gremlins if the reset bar is not exactly positioned and tightened.
Problems I have had in the past (as well as the above) have included ball not kicking into the shooter lane and the game credits continually counting down untill they reach zero. These have disappeared of their own accord, probably because I have swung over the reset units for switch inspection, and the retightening of the wingnuts has slightly altered something. Or pixie dust.
My present issue is that all seems to be working as it should except that when the ball hits a bumper or operates a rollover, instead of the expected 5 or 10 points, the 100 reel will clock up a hundred (sometimes more).
As this happens in lots of scoring positions, I assume it is not a playfield issue, but where should I start my visuals for investigating this.
As stated, I do have a schematic, but I'm not making much headway in understanding it (is it just me, or is it one of the dark arts...?)
Again, apologies to Boatcat. If you have any reserves of patience left, I would sure appreciate some pointers.