They are as good with belts as they were with my transport belt idlers!"I got a belt from deere, correct part number WRONG belt..."
Long runs of belt makes the idler alignment critical. If you can, run the machine w/PTO on engine @ idle and look at the belt as it runs. It should be readily apparant where the belt is being chewed up and which way it needs to be adjusted. Sometimes it's hard to judge the adjustments with the belt stopped as they move around when running. Do this before you get another new belt and correct the angles and "guards" over the pullies.
I don't care what anyone else sez, the belt has to be running to see the necessary correction adjustment. That's just my 2 busted belts experience with my JD 42 thrower... I "adjusted" the belt 5 times with it stopped and couldn't get where it was misaligned. Ran it and watched the idlers and "bingo", no new belts in 7 years.