I "think" the rear sprocket is the same as the newer model KDX's.
Tearing it apart and inspecting it sounds like a great idea. Bearings and gaskets are still available, though you may have to do some hunting. I see various gaskets and kits on eBay from time to time.
See if it is still plated. Since it is so old, someone may have sleeved it in the past. If it is plated and damaged, it can be replated. Here is one comapny with a very good reputation.
http://www.mt-llc.com/
Tearing it apart and inspecting it sounds like a great idea. Bearings and gaskets are still available, though you may have to do some hunting. I see various gaskets and kits on eBay from time to time.
See if it is still plated. Since it is so old, someone may have sleeved it in the past. If it is plated and damaged, it can be replated. Here is one comapny with a very good reputation.
http://www.mt-llc.com/