SB 569: Dunno, I have not |yet ?] performed a pre-purchase inspection on it.
Turbos: Probably, but could be insufficient oil supply as well.
Not sure about the TB21 install, but on the Cessna T210 & P210s, the turbo oil supply line comes off a " Y " AN fitting, one line going to the turbo and the other to the oil pressure gauge.
Very easy for a mechanic to get the two mixed up since both have AN-3 flared fittings.
The problem is that the oil pressure gauge side has a very small restrictor …
You guessed it, if the two were mixed up, the turbo bearings would get trashed after a few hundred or so hours TIS. Of course, this would be repeated until someone figures it out.