Best practice for dump valve/OPV installation

[Jersey1971]

This seems like it should be pretty straightforward, but are there best practices to make sure the rubber gasket is properly seated over the orifice?
I've been pulling on the string while I screw the valve on to avoid torquing the spring and rubbing the gasket against the rim and possibly damaging it. Is that necessary or even helpful?

I ask because I recently got a used wing with a slight leak from the valve. I couldn't see any obvious source of the leak and got variable amounts of leak each time I unscrewed and screwed it on. I happened to have a spare, which fixed the problem, so I wonder if the rubber seat was some microscopic irregularity that was letting air leak and if this might have been the result of careless screwing on and off.

 

[jakehbk]

What you've been doing is fine. It's what I do when I reinstall dump valves. Stuff will sneak it's way into those valves sometimes and muck up the sealing surface. Small rocks, salt crystals and other bits.

The spring can get a little weaker over time. You can get some more life out it of sometimes by gently stretching it out. If it still leaks after cleaning the pad and stretching the spring I just replace it.