Turn off the mower, lift the deck to the highest position and disengage the mower blades by turning off the PTO lever located on the fender.
Locate the drive pulley under the engine of your John Deere 175. It is accessible from the front underside of the riding tractor.
Remove the bolts that hold the belt guard over the pulley with your wrench and then place the guard off to the sidle.
Grip the belt with both hands and pull it off the pulley.
Place wooden 2-by-4-inch blocks under the left and right side of the mower deck and then lower the deck onto the blocks.
Remove the cotter pins and washers from the linkage rod pins and then pull the linage rods off the linkage rod pins.
Slide the mower deck out and remove the belt from the deck. Take note of how the belt routes around the pulley before you take the belt off.
Place the new belt onto the pulleys and then slide the deck under the tractor again.
Reattach the linkage rods to the tractor and then slide the belt over the drive pulley located under the mower.
Reattach the belt guard and then remove the wooden blocks from under the mower deck.