Down a rabbit hole, into the abyss.
Propane torch carefully applied on the disc to loosen the loctite, and it’s easily unscrewed (Diaphragm in no way gets damaged) Definitely can then screw the disc down for more preload on the existing spring. But will this alter its closing/opening without a stiffer spring. I really doubt it. Finding a spring with slightly thicker wire diameter in the .027”.-.029” range and close to OD, height and rate proving fruitless. But then there is this option:
Now we just need a lathe and some other equipment LOL. I’d just use a drill and a rod with a hole in it and improvise. Found some cheap music wire in the size needed, ideal for making a spring, enough to experiment with. Maybe:rolleyes: