LT155 transmission belt jumping

[Peclesswonder]

Hey all, asking as I can’t seem to find a solid answer anywhere.
I inherited a LT155 with the 42” freedom mulching deck that sat for a couple years outside.
After replacing the timing belt, oil change, other necessary things to get the engine running again things were going fine. I noticed that the transmission belt was also shot while I was under doing the timing belt, so replaced that too.
Am almost certain I got everything put back together properly, it drives well and nice and snappy. But, when I engage the blades, the transmission belt jumps off the rear diff by the fan. I can’t figure out what is causing this to happen so would appreciate any direction I might be able to check in. Thank you!

 

[mechanic mark]

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Are you using JD OEM Parts? check belt routing & 2 idler pulleys for drive belt right side underneath. Remove deck for access, scotch front wheels, jack up rear of tractor & give it a try, report back with findings.

 

[Peclesswonder]

Search results for Lt155 | Shop.Deere.com

Search results for lt155 on JohnDeereStore

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Are you using JD OEM Parts?

yes

 

[ILENGINE]

Make sure the transmission support bracket is connected the front or front corner of the transmission. If the support comes loose it will allow the transmission to rock which will throw the belt off of the pulley. Also can cause cracking of the mower frame were the transmission axles connect to the flat plates.

https://partscatalog.deere.com/jdrc/sidebyside/equipment/66977/referrer/navigation/pgId/80686434

Item 2

 

[bertsmobile1]

Apart from Illengines post above have a close look at the deck engagement rod
From memory that model has a solid rod from the rear which can foul on the transmission belt if either is out of place

 

[Peclesswonder]

Thank you all for your replies, I’ll try to get out to take a look at the recommendations after work today.