Not rebuildable, at least not worth paying for the rebuild. they clog unless special care is taken to get the right consistency. don't use high solids paints (any good premium paint) or they will wear very fast. We used to deal people that would bring these things in for "service"... we did spraytech/wagner/speeflo/titan/graco/etc warranty/fact. auth. work and dealt w/ big airless sprayers on a regular basis. Basically, the parts/labor cost more than buying a new one, saw probably 10 a year come through on 1-use kills. rent a good airless for a 1-time job, save up for an entry level airless piston pump or good used pro pump if you want to keep it around a while. IMO, any consumer level paint system (other than a roller and brush) is junk and not worth the $$$, but that's just me.