Here's a picture with the parts numbers:
http://tech.airsoftcanada.com/KJ/kj-g23s.jpg
Once you figure exactly which part(s) you need, send an email directly to KJW customer support at
kjworks@ms47.hinet.net, they usually answer pretty fast, considering they are on the other side of the planet. They will ship the parts to you directly. Their prices and shipping are amazingly low.
Hope this helps. :)