belt comes off LT1042

[bamaman01]

Now when I mow and lower deck gauge to lowest position the belt comes off after a short time. However, when I mow in position up from lowest it will not come off. I did notice that the idler pulley has a dip around the top edge, possibly that is what is going on. I know there is someone out there can tell me.
Thanks In Advance

 

[cadet]

When I had this issue, I found that the bolt through the center of the pulley was loose.

 

[zebcokid]

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Now when I mow and lower deck gauge to lowest position the belt comes off after a short time. However, when I mow in position up from lowest it will not come off. I did notice that the idler pulley has a dip around the top edge, possibly that is what is going on. I know there is someone out there can tell me.
Thanks In Advance

The second pully from the left on the top of the mower deck, as you are sitting on the mower, may need to be tightened. The bolt to tighten runs from the top of the second pully to the bottom of the mower deck. You may have to scrape away dirt, mud, and grass from under the deck to locate the nut as it will spin as you tighten the bolt from the top. Good luck...