Most likely, the first thing to assume is that the roll may simply be finished. A “24 exposure” roll often yields around that point depending on loading and frame spacing.

Safest approach: rewind the film normally and get it out of the camera before troubleshooting anything else. Protecting the exposed frames is the priority.

Then check what happens next:

• If the cassette turns out to be a 24-exposure roll, there may be no problem at all.
• Load another roll and test the camera. If it jams again at a similar point, the camera likely needs service.

If normal rewind is also stuck, avoid opening the camera in light. Use a changing bag if possible, then carefully open the back and manually recover the film so you don’t fog your images.

After processing, the film can give clues:

• Many blank/overexposed frames at the start can mean too much leader was used during loading.
• Unexposed frames left at the end can suggest the film never advanced correctly.

So: rewind first, save the shots, then test with another roll to tell whether it was normal film end, loading technique, or a camera issue.