TargetTalk

If these are like on the CPM-1, which I'm pretty sure they are, you don't disassemble the cylinder. You use a plastic tool (metal if you're very careful) to pull the old one out. Clean and lube the groove and put a new one in. It's a little tricky the first time, but just takes a minute or so with p...

Protek Supplies has them, 10 for around $30 shipped to the US. I've gotten parts for my old LGR and CPM-1 from them on two occasions, no problems. For shipping to the US email them and ask for instructions, they get back to you in a day or two.

http://www.proteksupplies.co.uk/walther-spares.html