There are several things to try.
1) polish the chamber, with 400/600 grit sand paper use an in and out motion, don't twist it in the barrel.
2) Call KT, ask for service, ask for a new extrator, extractor spring and several buttonhead screws. If the extractor has been jumping over the round you probabbly need it. Getting the old one out now that it has been lock-tited is gonna take some work. The key is heat. If you have heat gun use it, if not try a hair dryer, get that area good and warm BEFORE you try to remove the screw, they strip easily, and are 2mm in size.
3) Concentrate on keeping a frim wrist the next time you shoot. Just in case.
There is a newer style extractor out, there are plenty of older style ones that work just fine, If you weren't having problems I wouldn't worry about which style you have.
Link to extractor info.
http://www.ktog.org/cgi-bin/yabb/YaBB.cgi?board=2504;action=display;num=1145152844
Try options one and three out and let us know how it goes.