Old thread I know but I stumbled upon it by accident.
I think U guys are worrying about nothing, these fricken BA Turbos all make that sound when they spool down especially when they are cold.
If you have no play side to side,back & forward & she keeps a spinnin for ever when you switch her off then it's more than likely just the noise that these things make. They can be noisy on spool down & not under load (less noisy when cookin hot).
But just to be safe check the inline filter on the engine block for a clogged filter or even better, get an aftermarket one.

Or you could do what I do & just change you engine oil & filter regularly & don't even bother with a turbo filter. Never had a problem with it. IMOP Dirty oil would be better than NO oil at all.

just buy a new core for about $600 of ebay it has all the wheels and seals,all brand new .easy to fit you're self (get the genuine Garrett one ) they are all balanced and just a straight forward swap over .

Yep that's what CRA is .. Centre rotating assembly..