Old posts of mine from Weldingweb weldors here might find useful. Old Victor flowmeters and regulators are easy to find cheap while their new stuff is now expensive.

https://weldingweb.com/vbb/threads/5...225#post502225

Other quality US brands have kits too of course but this gives ya the basics. The seat is what normally fails and the noise of the blowoff valve is just the blowoff doing its job. This also applies to high pressure oxygen regulators (acetylene regs don't have a blowoff which would be an instant flamethrower!).