Slipping Belt Or Jammed Pulley ?

[new yaris owner]

1999 Yaris GS 998cc.

Went on holiday for 2 weeks, came back, went to start it and the belt that raps around the crankshaft pulley, alternator, power steering etc. is completely slipping. I mean only the crankshaft pulley is rotating, and the belt is static.

Never seen this before. Looks like something is jammed , or maybe belt tension needs adjusting. But the tension seems fine. Was OK before I went on holiday !

Before I touch the belt tension, (I don't want ot overtighten it). Is it possible that one of the pulleys can get jammed, maybe the water pump. ?

I'm new to the Yaris just trying to identify any known issues.

[new yaris owner]

I've now loosened the auxillary belt. And it's the alternator. It is jammed solid. Great !

Anyone any tips on how to remove and replace the alternator ? :(