I have a 1973 King Pin.
My issue is that the 1000 reel advances sometimes when is is not supposed to. For example, score 500 and get 1500 next time 2500.
Score reels rebuilt and seem to be working good.
Play field everything working.
This machine has a bank of ten targets. They can add either 500 or 5000 depending on specials.
During a malfunction when only the one relay should pull in, I can see both relays pull in and pulse for the 5000 and 500 relays.
I don't have a schematic.
Any good guesses on what to check next. Not much info to go on so ask away.
Thanks
Jay