Mr4082 shredding blade drive belt. What can cause this?

I would carry out the following checks: Make sure that you are mowing at the appropriate height, if the deck is set to the ground and operating at full speed this will create heat build-up and cause the damage to the belt. Check the blade condition. Make sure that the mowing deck hasn’t occurred any damage from being bashed, and check the alignment of the pulleys. Check the condition of the pulleys and bearings, this can put increased wear on the belt.