Walther cp88 nickel slide leak problem

[Aimstraight]

I think he means CP99. The photo IS the C02 Mag from a CP99.

The magazine and component parts are shown here.

The whole Mag is PW248 and quite costly.

PW340 is described as the valve assembly complete (the valve pin can be seen in the photo on page 2), held into the Mag by dowel pins DP317.

I would be tempted to strip it down, clean and lube it with Pellgunoil. Would not surprise me if it were bone dry inside, causing the seals to stick on the housing.

On the other hand....someone might have tried that before you to no avail.