Check your drive belt tensioner mechanism for worn belt, idler pulley, or spring. Yes, there is a hydrostatic transaxle which holds oil that is driven by the belt. I beleive the fluid on the 1330 is checked and filled by removing an allen plug located above one of the axle housings- check with owner's manual or dealer on that as there were differences among units. There is also a fluid filter used on this transaxle, but it is located inside the hydro pump and is not considered serviceable.
Changing the hydro oil (there is a procedure for it) or topping it off or fixing the tensioner might not solve your problem. The 1330 is an older tractor and I run into a lot of them for sale with weak or dead hydrostatic transaxles. The fluid on these is supposed to be purged and changed every 2 years, but many owners and dealers considered it to be a sealed and non-serviceable unit and did not touch it, thus many are now worn out and not worth repairing.
-Fordlords-
