Look under the cover, then lift the gears out. If any tooth is broken or bent, the whole train will lock. Check the shaft for a stuck bolt or rust—usually a seized pin is the culprit. Keep a small wrench for each size, you’ll want a set of those 8‑mm ones. If the gear teeth are intact, the problem might be a jammed worm gear or a stuck spur that’s been locked by corrosion. Try a thin metal rod to pry it free, then apply a little penetrating oil. If that still won’t budge, the gears might be welded together; you’ll need a hacksaw to cut them apart and see if any part is seized. Remember, if you can’t pull a gear off, it’s probably stuck in a lock. Then you’ve got to disassemble, check each tooth, and rebuild. Good luck.

Grab the 8‑mm and 10‑mm wrenches, feel for any bolt that’s stuck, and if it’s not turning, try a hammer tap to loosen it—no more poking until the bolt’s out.

Sounds solid—keep the clamp tight, give that bolt a good tap, and watch the shaft start to wiggle. If it still won’t budge, bring out the penetrating oil. Good luck.