sixstring, IF that shock is rebuildable (a lot of OEM shocks are not), John Sharrard aka Accelerated Technologies can do it. Brad Clarke aka Compulsion Racing can probably do it, also, and he is more local. That shock is a whole different ball game from the Marzocchi that Low rider is talking about; it's unlikely that you'll find parts at a hydraulics shop for it. BUT ...
What the good suspension tuners will probably tell you is that by the time you finish mucking around with that OEM shock, you will probably have bought yourself a used Ohlins, except that you will not have Ohlins to show for it, it will still just be an OEM shock. A friend of mine went through this with the shock for his 2000 R1 which lost all damping suddenly on a trip down south, and we had this same discussion. Fix or replace ... how long are you planning to keep the bike? "Forever" ... then get the Ohlins and get on with it. That was at around 30,000 km on the odometer IIRC. He still has it, with something like 90,000 km on it, and it still has the Ohlins shock.