Neff V5360XOGB – drum not moving – help needed please

Happy New Year all,

My Neff washing machine has developed a fault.

The other day it was being used as normal,
when it made a loud bang almost at the end of a program (2m left).

The machine completed the program but the the drum was no longer spinning.

I followed various advise online, and when I removed the back of the machine,
I could clearly see that the belt had slipped from its correct position.

I got some advise from “burns” on this forum,
and he recommended I try putting it back on if it was in good condition, which it is.

So I tried and then I noticed that the pulley on the back of the drum is rock solid, and does not move at all!

I then tried to spin the drum from the front of the machine,
opening the machine door, and again the drum was rock solid,
could not budge it an inch…

so clearly there is an issue here.

Also – I have supplied another image – I noticed this pipe is not connected to anything (circled in red),
which instinctively does not seem right to me.

Any opinions would be most welcome.