I just bought a JD 318 with a jerky hydrostatic unit. I've changed the fluid and filter and no change in performance. I did some searching on the web and it seems everyone just replaces the hydro pump when they have problems. I've run acrossed a couple websites that claim they rebuild them so I know they are rebuildable. Has anyone attempted to rebuild one themselves? I've rebuild several hydraulic cylinders and quite a few automatic car transmissions (including some tricky overdrive units) and I can't believe they can be that difficult. I also have a fullsized milling machine and lathe at home in my shop so if any major machine work needs to be done I should be able to do it myself. Right now I'm waiting for my tech manual from the Deere dealer to see if it has any info on overhalling the hydro pump.