I bought a used Iron Maiden and the lower right flipper keeps getting stuck. Not sure if this is a routed or HUO machine, but looking at the condition, I would guess HUO. Total lifetime plays are around 700. I pulled it apart and the coil spring is really dirty. I replaced it and it was a little better but still hanging. After around 20-40 games I pulled the coil sleeve out and it's really dirty again. Is this common? Could the coil be going bad and that's why I'm having issues? The return spring in on there and feels the same as the left hand side? Is there some sort of adjustment that I'm missing? When it gets stuck, I can power off the machine and it still stays up, do I don't think it's an electronic issue.

I've replaced the sleeve and cleaned the plunger with rubbing alcohol. The coil stop "looks" ok. If the coil stop is the issue and I swap them from left to right (are they interchange-able). Would the problem go to the left hand side then?