I have a copy of a manual if you want one, you can also buy digital copies online for maybe $10 that were pretty good. The hydraulic system is intimidating but once you think about how it all works it makes sense. I bought one that one side would always keep going forward even if you let off the handle, it basically took forever to find "neutral". I was able to fix the pilot valve with a few parts on the machine, you can service and adjust them.
I would suggest looking at the pilot valve in the belly of the machine mid/rear machine. You can see them with the cab up and the smaller belly plates on the bottom. They are probably about 12" diameter, and have an adjustment screw/nut on the top and bottom to change the limits of the travel valves. You would mess with these if the machine did not track straight when driving directly forward. There is one large valve for each travel motor on the machine.
Also, easy enough to pull the shrouding from around the control levers/handles and swap the pilot control hoses. Chance the control valve could be bad, although I don't think that is too common. It would rule that out though and it's fairly easy... basically swap the hoses from port to port, it would work "backwards", but if then the LEFT track is giving you this trouble after the hose swap you know the hand control pilot valve is the issue.
Late response, but I hope this is some help. They are fairly complex, but in a couple of hours you can read the manuals and get a good idea of how it all works. There isn't really a whole lot to go wrong- the only real 'computer' on these is if you have the variable aux. hydraulic flow.
Send me a message if you have other questions or need a manual still.
