If it's like Capt. Card (shown below), it could be a switch on the V/1st Ball relay (in red).
Capt Card Ball Subtract (resized).jpg
/Mark

On Capt. Card the V relay stays locked on until points are scored so if you drain without scoring the ball count won't change.

Have you verified that the schematic shown above matches your game?

Read up on continuity vs. resistance in this forum. Continuity alone doesn't tell you much. Unless you can measure a resistance of about an ohm or less between two points the meter is probably detecting some other, parallel path through the circuit.