While rebuilding my spare alternator...
https://986forum.com/forums/performance-technical-chat/87604-rebuilding-alternator.html
... I discovered that the pulley was seized (they are supposed to act like a ratchet, locked in one direction and freewheeling in the other).
So I verified the pulley on my base Boxster that I am selling... and found it was seized also. I bought 2 new pulleys, and installed one in the car. I have now started preparing my Boxster S for its Spring coming out (of storage) and checked the pully... also is seized. Good thing that I bought 2.
That makes 3 seized pulleys out of 3 that I have checked. I am curious to know what other's experience is. I might add that that the pulley on my friend Newart's Cayman also failed, it came apart while driving and threw the accessory belt off, leaving him stranded.