Husqvarna YTH24V54-drive belt wont stay on backside pulley

[kardoc]

The drive belt will not stay on the backside pulley when the clutch (left pedal) is derpressed.
it is a brand new belt and i am sure it is the right one. I tried to replace the pulley, but the bolt turns with the nut. I
don't see any way to get a wrench on top without taking the complete body off.
Watching the plate the two pulleys are on from the underside, you can see the plate and pulley tilt a little as the clutch is depressed,
I had read here in this forum that there is a bushing that will wear on top of the backside pulley and elongate the hole.
The backside pulley is the only one of the three that does not have a belt guide.
The mower was in to an authorized dealer about a year ago for a frame replacement under warranty due to the frame breaking in two at the usual place in front of the rear wheels.

 

[StarTech]

Yes you have to take the fender pan loose to get to hex head of the bolt. It because some penny pincher decide it was cheaper to use cap screws instead carriage bolts

 

[bertsmobile1]

I usually drop the transmission as it is just 6 bolts and a couple of links so I can get to the top pulley easily
The most common reason for the drive belt jumping off is the anti rotation bolts at the front of the transmission breaking off / coming loose .
This causes the whole transmission to tilt just enough to allow the belt to flip off the pulley
In the image below remove remove the split pins on the 2 control rods # 29 & # 163 and slide the rods out , noting the order of the washers ( Photos are good ) then the 4 nuts # 116 and bolts # 73 followed by loosening the bolts # 125 in the side frame to allow the plate # 80 to swing so the transmission is on the floor then remove the 2 bolts completely
Check the other 2 bolts # 125 and the bolts # 227 these are the ones that loosen or snap they have to be tight and there must be no movement between the plate # 226 and the transmission ,
I find it easier to do with the wheels removed others do it wheels on