Hi Pinside, I got a Space Mission 4-Player for $350 a while back, and am trying to diagnose some problems. This is my first pinball game, and my first EM machine, so completely new territory for me.

One of them is the credit reel. The game has been rewired for free play in some fashion, because I can just hit the start button and the game tries to start. When I do so, the credit reel attempts to turn over to 1, but it binds up and doesn't move. Linked below is a Google Drive with images and a video of the problem area. Any help is appreciated!
https://drive.google.com/open?id=1YjKIKY27BzyrBZ5kmeq3AI2qC59aVKoC

(Since taking the pics/video, I moved that one spring that's not held on by the hook, and hooked it onto that arm. That did not seem to affect anything, but that didn't look right to me, so I'll keep it on the hook of the spring)

Pressing it and letting go

Thanks for the advice. My gut instinct was to just take it off and clean it, but I figure I'd ask first. Will do research on the coil, I bought a tune-up kit that included 5 coil sleeves, so I've got the replacement part already. What should I use to clean it? I'm thinking q-tips and isopropyrol alcohol?