I've successfully rebuilt a few 240 racks years ago (before a stock of cores were available for rebuilders to get involved). It is not a simple matter like changing a crankshaft or front hub seal. The seals do not look like those at all. It requires complete disassembly of the rack -- a spotlessly clean work environment - and the knowledge and experience to "balance" the assist side to side with the valve assembly. If you don't mind spending countless hours working it all out then go for it. Maybe I'm on the lazy side but I'd rather spend the money and have it done right the first time and with a warrantee. - Dave