I've gotten rebuild kits from Mac1, JGAirguns.biz, and from a seller on eBay with the username Crosman600repair and business card that says Henry Ford. I like the kits from Henry Ford, and have used them for a variety of 1970s to 80s airguns. His 78/79g kits are about $30 shipped.



Look for a kit that includes a urethane (white) seal for the CO2 piercing cap and a new exhaust valve. If you'd rather keep your original brass exhaust valve, JGAirguns will rebuild it for you for $20. You do want to replace that valve. The cheapest kits on eBay don't include one. It would be a shame to spend a few hours disassembling, cleaning, and reassembling your pistol just to hear CO2 escaping the first time you pierce a CO2 cartridge!

As for directions, there are several videos on Youtube that have directions for disassembly and reseal.