I have a Mountech derail on a 85 Schwinn Le Tour Luxe and it still works fine. I looked at your cage position there on the Fuji and it looks right to me when compared to mine. Supposedly they had problems with dirt getting into the spring inside the third pully. If you can clean out the third pully with solvent then relube it should return to normal. But only do that as a last resort after all other attempts have failed.

History also said that Superbe Tech derailleurs were junk too, but I've one with over 150,000 miles on it and has never given me the least bit of trouble. Maybe when it gets to 200,000 miles something might happen to it then I'll scream: "god this crap was made cheap!"