Bought 4000D with SOS out. Guy had it on a generator overnight and it ran out of oil. Had a buddy work on it, spent $2,500 on it and it still didn't work. Something designed in the early 50s can't be that complicated, right? Wrong! Started disassembling trans on work bench with aid of double clutch manual. Found shop rag and large snap ring from clutch pack in bottom of case. This guy should not be allowed to own wrenches. Started from bare case reassembling bringing everything up to specs ,replacing as nessary. Installed trans in tractor and it still didn't work. Three gauges weren't even close to correct readings. Looking at box of spare parts discovered a control valve assembly. It was not the same as one in tractor. Stupid apparently thought the assembly was the culprit and replaced it with one fron the sprag clutch model. Installed correct one now pressures are perfect with only minor tweaking. Trans now happy. Motor had some roughness to it so sent Roosa master and injectors to pump shop. Now motor is happy. Did complete restoration. If time, sweat and blood were of value, this is one expensive tractor. Between 16.9 rears and 2600 RPM this little guys Moseys down the road. Everything works, it's as near perfect as I can get it. I think it's cute and will probably out live me!