The weight lock collars at the left are 3-4 feet above the top counterweight, and the ones on the right are probably 15-18" up.
That won't keep the counterweights in-place should you have a stage-heavy run-away. The arbor hits the top stop and inertia lets them keep on going . . . until gravity overcomes the flight pattern and it comes crashing down to the floor below; probably bouncing and boinging off of the adjacent metal, rope, and cables all along the way. Talk about an uncontrolled and unpredictable ballistic missile!
Here is what can happen when the weight hits the floor:
The force of the impact broke-off a 2" thick piece of steel! Imagine what would happen if it struck someone on the way down! Even an OSHA required ANSI standard hard-hat wouldn't help you.
Of course, stacking the weights on top of the weight locking rings won't help either . . .
So what else could we do wrong? How about no thumb-screws in the locking collar . . .