I had the joy of watching a Telex tape drive go into a runaway spin without a tape being mountedon it, the sight of several men running and ducking for cover, the sight of the hub exploding and the SOUND of shrapnel flying all around the computer room.
I mismounted a tape on a drive so that the take-up hub was spinning without gaining traction. I grabbed it. Big mistake. The payout hub took that as the signal that eveything was fine, so it started spinning out tape that floated through the air. I let go of the take-up hub, which caused the servo mechanism to go ape ... the tape settled from the air and got wrapped around the outside edges of both reels. That aggrevated the servos even worse; and, the next result is that both tape reels were broken and thrown off the hubs. All of that happened in a twinkling of an eye and a loud bang. God was with me that day, for nothing nailed me.
Each hub was driven by a one-horsepower motor and servo electronics that was truely bewildered. The unit was a Kennedy 8102.
Danger does lurk in innocent looking places.