Hey so ive looked around the forums and only come across this:
http://www.airsoftcanada.com/showthread.php?p=1513837
Unfortunately he does not show how to seal or fix the top of the mag....as some other users bumped the thread to find out.
I have two of my mags leaking gas from the top exhaust port, and no matter what I do I cant seem to seal it... not that I can do to much as I have no idea how to get at the top valves to fix them up! :banghead: