Change belt on snapper 722 snow blower - Agri-Fab Agri - Fab Snow Blower - 42"

1. Remove the belt cover with a socket wrench. Slide the belt cover off and set it aside.
2. Remove the two belt cover stud bolts with a socket wrench to get to the auger belt guide. 3. Remove the belt guide with a socket wrench.
4. Push down on the belt tensioner pulley with your hand. Remove the old belt and set it aside.
5. Install the new belt and release the belt tensioner pulley to tighten the belt.
6. Re-install the belt guide with a socket wrench and tighten the bolt.
7. Re-install the two belt cover stud bolts and tighten with a socket wrench.
8. Re-install the belt cover and secure it with the cover bolts. Tighten the bolts with a socket wrench.

I pulled the following from a snaper model similar to yours.
The snowthrower has two drive belts, one for the traction
drive-which transmits engine power to the wheels, and
a second for the auger drive-which transmits engine
power to the auger mechanism.
Each of these drive belts are of special construction and
should be replaced only with genuine replacement belts
which match the original equipment belts. These are
available from your dealer.
Traction Drive Belt Replacement
I pulled the following from a snapper model similar to yours. Believe it should help.

1. Disconnect spark plug wire and fasten it away from
the spark plug.
2. Remove belt cover. (Located in back of the discharge shute).
3. Pull the traction drive belt idler pulley arm (See
Figure 24) away from the belt to relieve tension, and
slide the belt off the engine pulley.
4. Slip the belt off from around the traction pulley (See
Figure 29) and pull the belt out of the unit between
the auger pulley and the traction pulley (the lower
cover need not be removed for this step).
5. Reverse the procedure to install the new belt. Be
sure there are no twists in the belt, and that the belt is
properly seated in the pulley grooves.
6. Replace the belt cover.
7. Start the unit, and check the traction drive for proper
operation. See "Traction Clutch Cable Adjustment"
for adjustment procedures.

There are also several videos on YouTube on changing snowthrowr belts. (Didn't see one for your blower, but most similar and should provide a good starting reference).