I picked up this elegant little 127-format folder recently on ebay. The Foth Derby was a contemporary of the early Leicas and had several features in common with them including a similar focusing mount and a cloth focal plane shutter with a 1/500 top speed.
When I held a light to the back of the shutter curtains and peered in through the lens, it looked like the starry night sky. To cover over the pinholes, I applied a coat of opaque fabric paint to both curtains. Not having any 127 film on hand to test the repair, I rolled up a strip of 35mm Acros inside some 127 backing paper to do some test shots.
The paint seems to have gotten rid of all the pinholes. However, I did get a couple of instances of a light leak across the frame due to the fact that a gap sometimes opens between the curtains if I don't cock the shutter with a single smooth turn. I may try increasing the tension on the curtains a bit.