And check the drive pulley for tightness (to whatever it's bolted or splined to), roundness, and condition of the Vee-groove. Also time to check the alignment of the two pulleys, and the driven pulley for the same things as the drive pulley. Also, check that the tensioner parts are correct - correctly adjusted, not bent or cracked, in line with the tensioner, etc. If there are things like drive shafts on the drive side or output shafts on the driven side, check any bearings or support for looseness or play.
There is a lot that can screw up a belt, so check everything. BH NC USA
I did check the vee-groove on pulley, did try to move pulleys and they did not move even a little, and when I had new belt on I checked to make sure it all looked straight which it did.. and it was super easy using that air cylinder to loosen the pulley ( such a cool concept)
and then we drove another 200 miles with no issues so I think I am good.. Have another 200 miles in 3 weeks so hopefully my new spare will be just that a spare that will stay sealed for many years