To the best of my knowledge, there are no service manuals for any chinese tractor, possible exception is that I heard norther tool may have written one for the JInmas. MOst maintenance information is in the owners manual (clutch adjusment, differential gear clearance, etc) the parts books show "exploded views" so you can see how things come apart (mechanical aptitude assumed). There is usually a troublshooting page.
I guess before I said all this, what broke? Also I think your tractor has a Yangdong Y380 engine, same as many 20 and 22hp Jinmas use. There is no AgTrac equivelant to the DF204 so our ability to help will be limited, but will do what we can.