would be able to tell you if it would fit. The new Scamp
13s are taller, but I don't know if the door changed, too.
I've seen a few cases where door fit issues were traced to a loss of support in the shell around the door. If so, replacing the door may not solve the problem.
I'd say finding a used one in good shape is a long shot. Most of the threads I've seen involved people making repairs to the one they had.
Perhaps you could tell us about the issue(s) you're experiencing (pictures are good) and I bet you'll get some suggestions. Hinge sag and loss of curvature (creating a gap at the bottom) seem to be typical old-Scamp door problems.