I have found that if the vanes get sticky a drive up a couple decent highway grades can cure it.
Sadly I have had the time to compare the vnt 17 turbine and shaft to the vnt 15 turbine.
The vnt 17 turbine is on the left. It's not the best picture but it's easy to see the size difference. Also the shafts are very similar in design. The vnt 17 shaft is a little bit longer on the compressor end since the compressor is also bigger.
Did it give any signs of letting go or did it just go boom
A few days before I noticed a slight, faint whine at higher boost levels. It never got worse and actually went away a bit. And then it just went bang on a second gear pull. Did you notice that the nut is still on the shaft?
Mine used to whine like a roots charger, then one day, it did the EXACT same thing...
no joke, SAME THING.. thought someone posted up my old pics for a second..
i actually abused mine for a LONG TIME before it finally went boom..
mine went boom 120 miles from home tho!!
my compressor wheel stayed slightly more intact tho, even after driving it 100+ miles without an intake hooked up to it
bearings and all 3 housings were wasted after that, and i darn near ran my engine out of oil as well..