If adjusting the plunger coil strength doesn't fix it, it's most likely an alignment issue. Regarding coil strength, sometimes increasing the strength can fix it, other times it might need to be decreased.

Check to see if the plunger assembly is secure and straight. Loosen the screws and try to adjust the angle slightly. Also check the rubber plunger tip that it's secure and not worn.

If balls remain stuck after you shut off power to the game, the problem is the balls are magnetized.
Try using the carbon balls if your replacement balls keep getting magnetized.

If the balls release when power is off and only stick during gameplay, try placing masking tape over the magnet below the playfield to help decrease the strength of the hold. (It may sound odd but it worked for me when the playfield monkey magnet on Woz wouldn't release )

Help. I’m having issues with the turntable/rotisserie. The motor turns but the turning mechanism with the metal peg that is supposed to grab the Geneva wheel gets stuck onto the Geneva wheel. It’s as if there isn’t enough space between the metal rotating mechanism and the plastic Geneva wheel.