Thanks, @Gero - saved me a bunch of hunting!
From the discussions about @mrhall4’s Gearbox failure - need replacement , it may actually be that having the gearbox as the mechanical failure point is acceptable… assuming we can source the internal gears.
Hopefully I can ensure it never comes to that - I’m currently thinking that, instead of my earlier microswitch cutoff (or in addition to it), putting a monitored load cell between the Top beam and the motor mount is the way to go. When chain load exceeds, say, 100lbs it hits pause / throws an alarm.
This adds circuit complexity, but keeps the failure mode non-destructive.
Besides, i’ve been having trouble figuring out how to spec the motor mount screws to shear within a predictable pressure range anyway. (my background is Electrical, not Mechanical Eng.)