Ha, didn't know it was a quiz show . It does sound like there's still something loose or broken in there. You pretty much took the whole top end apart there, so there's a chance one of the pieces isn't back in right. That's what I'd be thinking first- that I'd gotten something put back in wrong- thrust bearing backwards? screw not in tight? Or that there's something else dicey- did you check the mixing arms- they've been known to fracture in a crash? Are the dampers even and not damaged?

You kind of knocked the prime suspect off to start- that behavior's almost always a bent feathering shaft, so after that, it's checking that things aren't broken and they're all screwed together right.