It is a problem though. If you have 2 balls during a multiball drain and stack into the outhole at the same time the software never figures out where all the balls are after that (because it's counting them as they return instead of checking the status of all switches I guess, same issue with prototype Judge Dredd Ball locks on the ring). Even if you drain everything back to the trough. Typically have to power cycle the game to fix it. There are posts there to try and funnel the balls into the outhole 1 at a time but it still happens from time to time. Now I don't know if that's the case for the software for every single system 3 Gottlieb, but I've seen in on half a dozen titles.

Sega made a similar error when they switched from 2 coils to 1 coil on the below the pf ball trough. They initially forgot to add a ball stacking opto like on WMS games. So Space Jam (and possibly 1-2 other games) if the balls stack in the trough upkicker, that's it, game over man. The software never recovers as it doesn't kick the upkicker to try and clear the jam. I think this one is stuck even after power cycling and you have to manually undo the jam for it to recover. Explains why in later Sega and Stern software if the trough is missing a ball it will completely empty the trough. Surprises me still as it happens just as I am lifting the playfield to start working on the game.