PaulJM said:

There is excessive end float in the stator which has rubbed and worn through the wires.

Click to expand...

This is an interesting part! I noticed that the winding has been broken by the voltage regulator. You can see the wear on it:


But I don't really get why it happened. All the parts at the top of the alternator seem to be in place and in quite a good shape. I mean the bearings suck and I will replace them tomorrow but I don't think that will fix the tearing issue. It looks as if something was displaced and there was not enough space between the voltage regulator and the winding.
EDIT: or maybe it is the bearing at the top that had too much play...

PaulJM said:

The bearings are probably gone, throw it away and stop wasting your time.

Click to expand...

I know it would be wiser to buy another alternator (I may end up doing it anyway) but I'm doing this for educational purposes. I'm a total mechanical noob and I'm trying to understand and learn things here

Small update. You were right from the beginning - I should've bought another alternator I changed the bearings and then realized that the rotor is touching the stator as it rotates... I will buy an alternator from 300TDI and do a swap. I heard it's just a matter of replacing the pulley. Thank you for all your help! I regret nothing, I learned a lot

tomke92z said:

Small update. You were right from the beginning - I should've bought another alternator I changed the bearings and then realized that the rotor is touching the stator as it rotates... I will buy an alternator from 300TDI and do a swap. I heard it's just a matter of replacing the pulley. Thank you for all your help! I regret nothing, I learned a lot

Click to expand...

Glad you have got to the bottom of it.
Every day's a skool day!