I would try it yourself. It seems it may have been slightly abused by the previous owner. I would surely rebuild the ram cartridge. There is probably a lot of gunk in there. There is plenty of tutorials in the FAQs. I would have some extra 15/70 urethane orings though in case you clip some during disassembly/assembly.
When you absolutely, positively, have to shoot someones face off. Cyborg.