If you just tighten the screw at the bottom of the RBA, it's not enough to secure the positive screw block. You may also have issues with the center screw coming loose when the RBA is attached or removed from an APV causing intermittent shorts.
To secure the positive block remove the small center screw, #19. Hold the positive screw block to the negative screw block with a pair of needle nose pliers so it doesn't move, then tighten the center screw, #18.
Separate names with a comma.