If you can access the point inside the house where the faucet connects to the main water line, I wouldn't mess with trying to rebuild the old faucet. These are usually screwed into a female adapter that is attached to the supply line. It requires two wrenches to remove, one to twist and one on the adapter to provide counter force to keep from damaging the supply line. Reverse process to install the new one. Rebuilding will probable take more time to find the parts, disassemble the old faucet, and figure out how it goes back together than just to put a new faucet in. No access? Then rebuild is your only option.