Unlike CO2 rifles ( QB/ XS ) Co2 pistols should not be left "gassed" for any length of time. The seal that the powerlet is pressed against when loaded in the handle gets compressed and over time it becomes dis formed and will not re-shape, result being you load a new capsule and all the gas escapes as the powerlet is pierced.
First job ensure gun is unloaded and has no powerlet in it !! remove the handle cover that allows you to put powerlet in the handle.
need to remove the slide, undo screw at position A
Once this is removed you can remove the slide, the catch you open to put the magazine in, release it so the slide opens but hold the slide and allow it to slide forward from the gun , note the position of the bar , spring and washer.
next job is to remove the whole side of the gun , undo the indicated screws and remove them.
the safety lever comes off , put to one side, the whole side then comes off, you need to prise it up slowly , ideally use your fingers to get it started so as not to scratch the case with a tool , slowly lift it off.
this is the bit we are after :-
you need to Prise this out it will come away as 2 parts where you see the green line in the picture these are 2 separate parts the square part has a spring and a small brass tube, remember how these go together for re-fitting, one you have removed the block you can undo the ring that holds the seal , a 1/2 inch chisel fits perfectly
once undone pick the old seal out and replace with a new one
putting everything back is the reverse of removal, things will pop out and move so be careful and try to remember how everything goes - this picture below will help
a couple of these pictures have been taken from an article in the Umerex Boys Club Forum that shows stripping the gun down , this was also included in Airgun world magazine
article is here http://umarexboysclubforum.myfineforum.org/about8107.html&highlight=
the job is fiddly so take it slowly, don't press the safety bit down because a tiny ball bearing and spring pop out, its very fiddly to put them back, just go slow and don't force anything.
