I have this one droid. Andale stated they didn't have any parts. If you find out where please advise. This gauge has a hole in the diaphragm so if yours is OK perhaps parts for you?
Andale bought out Downey some 30+ years ago, so if anyone is going to have off the shelf parts, it will be them. It does not surprise me that they don't have parts,- they would much rather sell you a new reg.
I have found when confronted with a regulator challenge, that Gascon are really helpful, and are usually very reasonably priced. If they were to tell you to scrap it, I would believe them.
It is difficult to tell from the 2 pics that @droid & @Grott have posted, but I have my doubts as to whether these regs will take full cylinder pressure. I would investigate this as well whilst looking for parts. It may be necessary to use a knock down reg for safety purposes. I know that early Andale regs required the use of knock down regs. Most Downey equipment was before my time.