I seem to have a problem with the hydro transaxle in pullling a load up a hill. It seems to make a noise and barely goes although the engine seems to have plenty of power.

Hi,
Could be a worn belt or transaxle low on fluid. Usually on can find a dirty spot where fluid has leaked if that is it. The bad news is that the manual does not give a parts breakdown, just the occurrence of a Spanish version. It is at:
Owner's Manual - CRAFTSMAN Lawn, Tractor 917276905, 917276903, 91727690, 917276904, 917276900 - ManageMyLife.com (http://www.managemylife.com/mmh/owner_manuals/17002/CRAFTSMAN-Lawn-Tractor-L0704327?brand_name_search=91727690)
Peace,
Clarke