Congratulations on your "big" Terramite. I have had a 2004 T9 for a couple of years now and really love it. The thick steel makes my Kubota tractor feel like a tin toy. Digging and lifting are a joy, but travel is fairly slow, so don't plan on any long trips between filling and dumping.
As far as I know, there are only 2 manuals available for the Terramites, the Owner's Manual that you should have in the behind the seat case and the Parts Manual. The latter is online at the Terramite site. The parts manual really shows all there is about the Terramite. They are really simple to maintain and you can get at most everything very easily. If you have a problem, just call Terramite at their 800#. For me, their support has been nothing short of amazing. The support guy stayed on the line with me for a half hour, as I worked on a parking brake that had been installed backward.
The engine is a Kubota industrial engine and the manual for it is available from Kubota. Parts and service can come from either a Kubota industrial dealer or a Kubota tractor dealer, as virtually the same engine is used in tractor models.
Make sure you change the cartridge pre-filter that is under the floor board on the right side, in addition to changing the canister fuel filter. I didn't know it was there, and couldn't figure out why I was losing power, even after a filter change.