Phew, recently had one of these pistols for repair. Not my usual field I have to say. Co2 just pouring straight out through the barrel. Almost no info out there, so fly by experience and hope. To be fair it wasn't as bad as I expected, no real ''flying parts''. Sourcing O rings wasn't that easy, some just don't like Co2, but my local suppliers BSL Walsall managed to offer several choices of material, for all but one ring which is a 1.2 mm section; which they don't stock. It seems metric O rings are not at all straight forward, some countries use different increments ??!!
Anyway success, the O rings worked ok; lost count of the hours involved; no profit after buying O rings, but satisfaction by the bucket load. More important, a gun still in use.