Update: Checked all the fluids to turbo, all pipes clear and no obstructions. Took core out today, it had an apparent leak at the compressor side, 2 compressor bolts were not tight, that seems most likely cause of boost failure.
Core otherwise clean and wheels perfect, shaft spins smooth and with no more play than the replacement SS core sent me.
Think I will reassemble with same parts and see if I have boost. While it would be truly weird to have two turbo's fail for different reasons this close together in time, its possible. Oil pressure gauge did not come in today, so will just cold crank to make sure oil feed is working.
Update 9/25: Put it back together and works fine. So, second boost failure unrelated to first. The evidence as to what caused the first is gone, like the phoenix a C39 is arising from those Cyborg ashes, stronger and better than before. Or at least that is the story I have been told. We will see when it shows up.