Did you connect something back up improperly in the linkage between the hydro control handle and the lever on the trans?
I bet your belt has a twist in it causing the pulley to spin the opposite way. Or maybe the linkage arm on the bottom of the trans spun all the way around.The linkage is correct. On that model the only way to hook it up is the bolt from the bottom of the hydro lever to the f/r lever from the hydro.
Belt is connected properly.
Should note. I have it jacked up and the wheels off. Does that matter? Seems like it shouldn't.