Max-Flo on/off o-ring keeps getting nicked

[TheTramp]

My Max-Flo on/off o-ring keeps getting nicked so the tank can't shut off. The gun is constently aired up and the gas slowly (like over night) leaks out.

I've replaced the o-ring twice.

This just started to happen. Is there something I'm doing wrong when I take the on/off assembly apart? It seems pretty straight forward.

[TAW]

I nicked a few orings when I first got mine. Then I noticed that when I first turn it on is when I cut them. The problem was that it has the full tank pressure against the oring and turning the lever on fast chops the oring. I then started turning the lever slowly then stopping when the air first starts flowing. Once the reg is up to pressure you can open the valve all the way.

[TheTramp]

OK, I'll get another o-ring and give the slow turn on a try.

I wonder why it started doing it after I'd had the tank for a while.