When I engage the blades on my 917.256524 the belt does not spin is there a tension adjustment for it?

Sure is http://www.searspartsdirect.com/partsdirect/part-model/Craftsman-Parts/Riding-mower-tractor-Parts/Model-917256524/0247/1509200/10043201/00010?blt=06&prst=0&shdMod=917256524 there are three pulleys on your deck. One is on a moveable arm held in place by a spring. A threaded rod can add or subtract tension to the belt.

Thank you for the info I will give that a try.

Where is this treaded rod. I put a new belt on and my blades won't engage either. I was looking for a way to tighten the belt. I have a Craftsman 42inch 17.5 LT1000.
My blades engaged for a few days after I put the new belt on. Then it took about 30 seconds to engage. Now it doesn't engage at all

Where is this treaded rod. I put a new belt on and my blades won't engage either. I was looking for a way to tighten the belt. I have a Craftsman 42inch 17.5 LT1000.
My blades engaged for a a few days after I put the new belt on. Then it took about 30 seconds to engage. Now it doesn't engage at all
Do you have a manual? Look for the pulley that moves when you engage the belt, it swings on an arm. The rod that causes this pulley to swing is pulled by a rod which is threaded, there is your adjustment

do you have a manual? Look for the pulley that moves when you engage the belt, it swings on an arm. The rod that causes this pulley to swing is pulled by a rod which is threaded, there is your adjustment

Thanks