1. Tighten down the switch packs on your score reels. There is a set of points on each score reel that comes open when the reel hits zero. Make sure this is happening.
2. I don't have the schematic. There will be a relay or stepper unit that controls which player's single digit reel advances. If it is a relay, tighten and adjust the relay.
3. There should be a stepper unit that controls player and ball in play. When you reset the game, be sure it goes all the way to 1st player 1st ball. Some games actually go below that and step up one step at the end of the start game routine. The cog wheel on the coil side of the stepper has pins that stick up and engage the switches and stop the wheel turning. Check the adjustment of those switches.
Good luck