"Dave W" wrote:

Strain gauges don't have springs. My bathroom scales have feet
suspended on flat plastic spirals to allow them to move. They
press on the strain gauges underneath that are fixed to the solid glass
base.

Yes, my scale is the same (minus the glass base). But the flat plastic
spirals, whether you call them springs or not, still strike me as a weak
area, even though the amount of travel of each foot is restricted, as you
say, by the strain gauges located immediately above.

I'm intrigued by the fact that two of the four feet are connected to the PCB
by very fine twin wiring. The uppermost part of each foot, the bit that
presses against the gauge, appears to be metallic, but unless there's more
going on inside the rest of the foot than seems likely, why *two* wires?

If it's just one of your feet that's come off, not the gauge
underneath, then you're probably just experiencing the scales
sometimes pressing on three feet instead of four.

Yes, I think you're right. Thanks for the thought.