I think mine run at around 350-400psi, I'll air one up and check when I get home. I have a couple extra regs if you need a new one, your spring pack could be worn out.
You can use spyder cup seals, just thread them onto the pin/stem, probably need to use pliers to get the old one off. But it sounds more like the seat on the valve has a scratch on it, take it out and sand it with a fine stone, lapping compound, sandpaper on a block, however you do it just make sure to keep it good and flat, then polish it up nice, should take care of your leak. The leak might also be causing the pressure to not stay steady if the leak is bad enough.
Last edited by coldy13; 03-17-2012 at 07:54 AM.