It looks like the pulley itself is replaceable. I see an e-torx bolt holding it on.
https://www.ecstuning.com/b-gates-pa...287594969~gat/
11287594969 - MECHANICAL BELT TENSIONER
https://www.realoem.com/bmw/enUS/sho...diagId=11_4768
I’ve been unable to find just the pulley.
Anyone have a Dayco (or other manufacturer) part number?