So I received a 68/45 in the mail with a standard ninja reg... stupid as I was, aired it up before checking the internals. The tank leaks like crazy and spews air out. I find out a few days later that the guy I bought it from just threw the shims in the reg and forgot to mention it to me. So the shims are in some kind random order and I'm sure I destroyed it. The tank reads 4k on the gauge. I try to air it up through the gun - doesn't work. I tried to press in the little pin - doesn't work... I can even press it in w/ no problem, like the tank is completely empty. Which tells me the reg is done for? So how would I go about depleting the air so I can take the reg off to check it?