The only thing wrong with the typewriter was that someone installed one of the ribbon spools upside down (so the typewriter wouldn't automatically reverse the ribbon when it came to the end of the spool). I wound a new ribbon onto the spool, installed it correctly, and the typing machine worked fine.
The case for this portable typewriter was another matter, however, so the rebuilding of the case is what I'll focus on in this Instructable.
Step 1: Evaluate the condition of the case
The fabric on the inside of the case was still in good shape, so I decided to leave the original as it was.
Because the black finish of the fabric on the outside of the case was powdery and flaking off, attempting to repair and re-glue the original fabric was not an option. So, I decided to rip off all the old fabric and attempt to recover the case with something that looked like the original.