Burst disk and valve have nothing to do with his ASA. Burst disk is on the tank, and valve (depending on which one you're talking about) is on his tank or in his marker.
He is talking about a leak in the on/off of his ASA (from what I gather, he has an asa with an on/off screw. In this setup, a screw in the front of the ASA screws into the pin valve on the tank to gas the marker up. If I'm wrong in my assessment, than you may ignore the following). The screw on the front of your ASA may need a little teflon tape or loctite to keep air from leaking out of it. Take the screw out and put either some liquid thread sealant (such as loctite) or teflon tape on it. Put your tank back on the ASA and screw the screw back in. If air still leaks out, get a new screw. If that doesn't work, you're SOL I guess.