Check what Sam said. There is a grease fitting on the axle (#20) that may have got overlooked.
https://www.cubcadet.com/en_US/conte...0d87009d4452/y
If that checks out okay then inspect the nylon flange bearings(#19) on the pto assembly. I had some that failed causing my belts to smoke. There should not be much movement in the assembly.
https://www.cubcadet.com/en_US/conte...59d42274fbbf/y
If all that checks out okay I would pull the cover off of the gearbox on the deck. I'm not sure which deck you have but if you stand it up so the cover is facing up you can suck the oil out and inspect the gears and see if there are any damaged teeth.
I have had good luck using these fine belts.
https://www.ebay.com/itm/11310623421...EAAOSwZupgEtPv
Good luck and let us know how it goes.