first thing to do is deturmine which hole on the asa its leaking from.
look at the underside of the asa you will see 2 small holes.....if it leaks from the rear one (nearest where the tank screws in) then all you need to do is change your tank oring.
if it leaks from the front one..
take your tank off, then look into the asa...you need to remove the silver metal assembly you can see, easiest way is to tap it into the palm of your hand and it should drop out after a couple of taps.
you will notace that the part in your hand is a pin which slides thru a metal tube....the oring we are looking for is the one on the end which seals the pin to the tube.
first try a drop of oil on this oring, drop the insert back in the asa and gas it up.....if that doesnt fix it you need to change the oring. if you need to get hold of an oring ask your local eclipse service centre or drop firstname.lastname@example.org
a quick email and im he will hook you up with a couple.