Been having an issue with the autoplunger staying stuck up intermittently on my AFM. After it fires I can see the plunger rod staying up and can hear the coil energizing / feel some vibration through the right flipper button.

It looks and feels like it is sticking mechanically as opposed to through some actuation problem. Video of moving the plunger by hand where you can see it sticking sometimes:

I took this machine out of storage a couple of months ago to find this coil dead, so this is a brand new coil. It does look like the end of the coil sleeve has a little fraying already, so maybe that is contributing (or a symptom of another problem). But the machine will also go through fairly long stretches without the problem occurring. Any ideas?

Thanks all. Pretty sure the coil has not swelled since the action through the coil is really smooth until the very end. It does seem to be getting hung up in the back circular part so I might try cleaning/sanding that out, or maybe just buying a new plunger. Appreciate the fast responses.