Contact oneof the dealers who sponsor this site and they'll either have the manuals or know where you can get them. Chinese tractors typically come with four manuals: The User's Manual for the tractor, the Parts Manual for the tractor, User's Manual for the engine and Parts manual for the engine. You really need to get the full set in order to have the information you need to handle maintenance and minor (or even major) repairs. They tend to be written in “Chinglish” and can be a challenge to interpret a times, but the information is there and generally accurate, if expressed in terms you may find a bit confusing or even amusing at times.
The dealer/mechanic who called your tractor a POS is one I would expend some small effort to diminish his business. If they don't want to help you and take your money, fine. But disparaging your machine simply because it is Chinese or because you didn't buy from them is just childish and stupid business. In all likelihood, a significant portion of whatever “domestic” brand he is peddling is actually outsourced to China for manufacture. The time for that sort of petty jingoism is long past.