Craftsman 917203910 how to replace transmission belt

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shuttle valve(s) ar not in the full on position, or a loose belt. use craftsman belts on the craftsamn mower to avoid the BELT ISSUE
shuttle valve allows the mower to roll freely for nonrunning repairs service. ''hydrostatic transmission''

First replace the drive belt. (1/2 x 82-1/4) and the V-idler pulley if plastic, Reverse doesn't load the belt as much as forward drive. The reason I suggest replacing the V-idler too is that the plastic wears heavy and the drive belt bottoms out causing slippage.

Then if it doesn't drive forward then you most likely have a bad transmission.

sounds like the barrings in a ideler pulley are bad.

May slipping or wrong belt.

Remove blade and loosen tension system slide belt over transmission and off of the engine

it sounds to me that the drive belt needs to be replaced

The Craftsman drive belt #140218 is a 1/2" by 84.3" belt with an aramid fiber wrap.

Since this belt is contacted on both sides (inside and outside) as it runs the pattern on your mower, it must be replaced with another belt of exact size and construction. If you were to use an 84" belt, then the tension pulley would not have enough slack to disengage the transmission. Likewise, an 85" belt would have too much slack and cause the trans to slip.

The original belt is available through www.searspartsdirect.com for about $25 plus shipping. Check with your local lawnmower repair shop, they probably stock this belt and will be competitive in price.

Good luck!

Its not a hard job just push in clutch and lock it, remove mower belt then replace drive belt and then put mower belt back on and release clutch.

check to see if the drive belt has slipped off