During a single player game, this isn't an issue, but during mulitplayer games here is what is happening:

Player number 1 locks a ball using the ramp and the electromagnet. It holds it in that small raised wood section on the left of the playfield. This is normal.

Player 2 takes their turn and locks a ball as well. This puts 2 balls into the lock area, and normally the game will drop the first locked ball, leaving just a single locked ball up there. This isn't happening. Both balls are staying locked long enough for the game to go into the "ball search" mode where it fires the solenoids around the playfield and the last thing that it does is fire the one that drops the pin to release one ball. The game can now continue.

This is obviously not correct for it to put itself into the ball search mode. I did a switch test and it registers both switches (one to reflect the first locked ball, and the switch to detect that there is more than one ball locked. Obviously the solenoid to release the pin works too.

It doesn't stop people from playing it, but it does really mess with the "flow" and obviously isn't correct.

This is on my in-law's recently acquired machine. It was doing that since they got it a couple of weeks ago, and this weekend I tore down the playfield to clean everything, replace bulbs, put new rubber on, fix the weak plunger, rebuild the flippers, level the playfield from right to left, put in the correct pitch, etc. It plays great now, but that darned locked ball issue remains.

Thanks!

Thanks for the tips. I will pass them along tonight. I tested it with my finger during the switch test. The switch "arms" look like they would only be activated one at a time, but maybe the second one isn't moving far enough when there is a ball in there.

Seems so obvious now... test with whatever is actually going to be activating the switch (use the ball, not a finger).