Quoted from MarkDPar:

reposting this in the hope that someone has since figured it out - because I have the exact same issue on my TZ. I was excited to see the match come up on my search but so disappointed there was no resolution. I emphasize that it acts just as described below - the magnet just doesn't let go. When it does the ball check, you can often jostle it loose without tilting it but that's it.
"I'm a new owner of this classic game. Twilight Zone: when the left spiral magnet catches a ball for various reasons, the ball is held there until the machine starts looking for the lost ball, and at some point one of the checks is to release the ball from that magnet. Until the check releases that ball, however, it is hung there indefinitely, and the magnet has too strong of a hold to nudge the ball loose of that magnetic hold.
Is this a known issue? Is there a known fix?"