1st gear vibration

this sounds exactly like a problem i had when i was chasing a vibration at launch/engagement and low initial rpm. i had *thought* the flywheel was fine and dandy because everything else was so waxed ***. turns out it was well out of spec and ate up a fresh clutch or two before my lizard brain caught on.

but not after a rebuild and throwing a bunch of parts at it, because of course...