Are you sure the magnet pole or the balls haven't become magnetized ?

LTG : )

Is the magnet level with the playfield?

Those were the two that came to mind for me as well. Both magnets in my spiral were well below the playfield when I purchased my TZ. They were fairly beat up anyway, so I swapped them out with new cores while adjusting.

I had this problem on my Dirty Harry. It was the beat up core not being level with the playfield.

EDIT: To clarify what is actually happening, the ball is getting hung up on the edge between the steel core and the wood play field, sort of like it's sitting in a ditch

There's another simple solution. You may have the wrong grade or type of balls. IOW, the ball itself has become magnetic.

The reason for this is that powering down the magnet would not normally be part of the ball search procedure and if the magnet was locked on you would blow a fuse, transistor, etc. Not ruling out that possibility but it would be more likely the vibration caused by the solenoids firing is releasing the ball.

If you turn the game off when the ball is locked does it release?

So I had a similar issue with my TZ but with the right spiral. It locked on and burnt the PF but mostly the underside. Maybe the eddy board?

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?"

Magnet pole magnetized ? Optos for it not working ? Balls magnetized and sticking to it ?

LTG : )

My right magnet used to do this - it was a combination of the ball being slightly magnetized, and the magnet core being just a touch low on the playfield. So the combination of the slightly magnetized ball and the tiny lip created by the low core was just enough to hold the ball hostage

MarkDPar did you get this fixed - if so what was the issue?