Aimtrak Recoil Jamming — Please Help!

[galla22k]

Put together my first arcade over the summer. It has 2 Aimtrak Light Guns with 36v recoil on each. Has been working perfectly for months, but now all of a sudden, the one gun's recoil has stopped working. The aim sensor, trigger and side buttons are all still functioning properly.

I opened up the gun to diagnose the issue. Began resoldering connections. No luck. I believe the issue is that the plunger is physically getting jammed in the solenoid. So when I fire on-screen, the plunger recoils and gets stuck. I fire again, it doesn't push back out so there's no recoil effect. When I slide the plunger back out by hand and fire again, I get the same result. Recoils & jams.

I've cleaned the plunger and inside the solenoid as best I could. Even applied some light oil to it, as Andy suggests on Ultimarc website. The spring is still on the plunger, too. But no matter what I try, it just isn't pushing back out.

Anyone have any suggestions/ideas for troubleshooting?