Just to add to the discussion- I have had problems with both of my spinners where I have powered it up with the locking pin in, it turned out that the motor was actually turned on! So it burnt out the motors which was annoying. If I hadn't had the pin in I woul have seen it start to spin and could have just ripped out the link immediately.
Although it could be argued that it was a good job I had the bar in otherwise it would start spinning and could hurt someone, so I am not really sure what my point is!!