WHOA, they put a 7500 disc on your low side, are they idiots???? the reason that disc is going out is becuase the reg is not regulating, even if that worked, it would mean you would have been putting in the full 4500psi into your gun directly. VERY UNSAFE!!!!!!!!!! two things you can do, one send it in, or two buy a new reg for the tank.
If you have a problem with your Air system, post it, I'll try to help you with what you need to do to fix it, and where you can go to get parts. AAchopshop is now open on ebay http://stores.ebay.com/AA-Chopshop?refid=store