I think I've got the Falling Z-stage issue licked! I figured what the problem

I think I’ve got the Falling Z-stage issue licked! I figured what the problem needed was a clutch or brake, but couldn’t figure out the easiest way to do so. Playing about with a bit of GT2 belt, I recalled a mechanism that would drag in one direction only, because it had a spring on a belt that was only pulled tight in one direction. Looking at the video, I plan to have a mount with two springs, tension for raising and lowering the bed.

The video is with the full weight bed, roughly 6 lbs. I plan on lifting it with two motors, as someone intimated that that was about the max lift with one motor.