KWA m226 parts

[Rogers84]

I have a pretty old KWA226 which seems to need some new parts but struggling to find a stockist, it was a solid gun until it started discharging all the gas from the magazine with the 1st shot, wondering if I need to replace the release valve on the magazine or if it’s something to do with the gun, also when I took the top slide off I notice some green plastic which I found came from the main seal. Any help on what I can do to fix and get parts is greatly appreciated

 

[Ronin0033]

Pretty sure this will just be the main piston cup (the green bit!). KWA ones tend to disintegrate if left dry. 
You can by a new one, or swap for an o-ring type piston head, available at Lees Precision Engineering.