assuming ball lift cam switch #1 is not stuck closed or shorted (lifter will run with no balls in the game), you need the lifter start relay to power to stop the ball lift motor. The naming of the lifter start relay is kinda backwards for historical reasons.

the ball runway switch in front of the shooter powers the lifter start relay, and the ball gate switch at the top of the runway unpowers the lifter start relay.

if you have the playfield tipped up against the head and the balls start lifting and dumping down into the cabinet, push the runway switch closed with your finger to stop the lifter from raising another ball.