So I'm pretty confident its a belt problem. Taking the load off the alternator with a battery charger allows the belt to grab the pulley and start spinning. Upon closer inspection the belt is cracking and glazed on the sides. This will be the first time ever the belt has been slipping without any ear piercing screeching sounds. The pulley is also smooth as glass. I'm going to build a better bracket for tensioning, get a new belt and see if I can't sand blast the pulley somewhere or perhaps flap wheel with my dremel.
Wow, you mean a new belt would have solved the problem in the first place? That would be so bad.
I think the mounting hole on mine is different because there is no way in hell the arm would reach it. Is your alternator Bosch?