I would imagine the only rebuildable items on the carb are the O-rings. And a rebuild in this case is really a "clean up" job. Sometimes there is gunk build up from Castor but that is about all there is to it. To get rid of the Castor build up, boil it in a pot water for 15 or 20 minutes, and flush it out. O-rings you will need to find in the parts list and order them up. Good luck.