I would also send off the camera to Mr. Ye. I had shutter issues with a IIIc and he repaired the camera and replaced the shutter curtain for just a little over $200. That is about what I would have to pay for another camera on eBay that would still be likely to need repair. I now have a reliable camera which should work we;; for many years.
If this happened to one of my FED cameras, I would simply pull on the shutter to see if it moves since those cameras aren't worth paying to get repaired.