...BTW your Bieber avatar is awesome.-Malone
Is the turbo VSR balanced once assembled? If not, vibrations are one cause of things magically disassembling themselves...
It would be fairly easy to test. Add an EMP gauge. Watch them both and see if the drive pressure drops off faster than boost when you let off the pedal. If it doesn't, then the turbo builder messed up. If it does, then add a BOV that keeps the intake pressure at or below the exhaust pressure.