There is two idler pulleys on that set up that might be bad. Actually the pulley under the crankshaft pulley is a idler and the pulley to the left side of the crankshaft pulley is a tensioner pulley. Either could be bad. They are the same pulley as Grasshopper loves to simplify things! Also there are three bushings in the tensioner arm that could be worn out and hanging up. Here are the part numbers for everything and hopefully I can upload a schematic of the drive belt system. I will put prices with the part numbers just so you can estimate how much for those items.
Part name, number on the picture, Grasshopper part number, prices
Idler pulley, 11, 393195, $18.55 each
Pedestal Bearing, 5, 121651, $4.70
Oilite bearing, 38, 121756, $0.65 each (need 2)