Yes, thoroughly clean all the Jones plug connections first... You'll probably need to use your schematic to trace one of the circuits on a 1000 point feature in one player mode. Just start from the transformer and trace it on your schematic all the way to the first player 1000 point score reel solenoid and you should be able to find the problem...

So, when you say "locks on" you mean the score reel coils are constantly energized? Try to isolate one issue. Take the 100 point score reel on the 1st player. What switches send power to that score reel coil? Check the following:

100 point relay - switch with white/orange wire and red/green wire
Reset relay - switch with yellow wire and orange/black wire
100 point score reel zero position switch - switch with orange/black wire and grey/green wire
Tilt relay - switch with yellow wire and white/orange wire

Also check all 100 point playfield switches...

If the point relays are sticking then you need to thoroughly clean and adjust the contact points on the 10, 100 and 1000 point relays. You need to get all the carbon off the contact points.

If there's no scoring, then you'll need to look at schematic again. Take the 100 point scoring on the 1st player. If the 100 point relay switch closes (switch with white/orange wire and red/green wire on the 100 point relay) it will send power to the player unit and then the power will be sent directly to the 100 point score reel coil.

Check to make sure the player unit is operating properly and it is positioned on the 1st player contacts.