Yes, you can check. Turbo shaft must turn freely with no rough or sticky spots in rotation, and must not have any axial play. Some will have radial play due to the nature of the bearing (it's a floating design).

If it is bad enough to leak oil, it will have rough spots, will have excess play, and will be coated with oil.

And, a dead turbo is VERY quiet, since it won't spin until you really stand on the accelerator.....!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!