Blower noise / knocking at high speeds

[bonbon]

Had this problem and found this description after I fixed everything.
As cars age this will happen to many.
Blowers available online for about 50quid (Amazon and Aliexpress)
blower noise/bmw blower motor replacement - YouTube

 

[Jack Ratt]

I had the same problem a couple of years ago. I got my replacement from Euro Carparts