Seems like bad turbo. Need help!

[Konstantin Bogach]

I looking into K-26 outlet and I think that something is not right:
edges of vanes are worn like after rough file and when I spin shaft it
come to stop very quickly (about 1sec) compare to K-24 in another car I
have which spins about 3-4 sec before it stops.  I am not sure it
happens just because K-26 is bigger.   What might be a reason for that?
I don't know exactly how turbo is built inside. I have Bentley but I did
not see it shows turbo internals.  What is usual cause when  turbo needs
to be rebuilt?

Thank you.

Konstantin Bogach.
200tq '89 (K-26)
200tqa '89 (K-24)