Right just to clear up a few details.! The vibration and noise is caused by compressor airflow mismatch through the
gas path.
In normal operation the engine would never been operated at above say 70% N1 immediately prior to being shut down. However heavy use of the reversers should invoke the requirement of the 20 min cool down cycle. The bowed rotor effect is a GE thing, very noticeable on any subsequent start, you definately don't need loose fillings.. or kidney stones
The STB (Start Transient Bleed [valve]) was removed very early on in the engines service life, as it was found to be unnessessary! The Bypass Valves (10 off) are fully open during engine start and dump excess air from the back of the LP compressor (booster) into the fan stream they only start to modulate closed with advancing throttle, the VSV (Variable Stators) are fully closed at idle and only start to modulate open with increasing throttle.
