Sylvia Else wrote:
The sustaining pedal[...]is become rather flaky[...]
So I disassembled the piano enough to get at the mechanism
[...]and was rather surprised to see that the business end
consists of a potentiometre.

Decades ago, on a Lowrey organ IIRC,
I saw a lamp and a photocell used in the expression pedal.
The pedal actuated a plate with a slot cut in it.
The plate separated the 2 devices;
the slot expanded from a slit at one end to wide at the other.
No noise from the device and wear wasn't an issue.

I'm not really surprised that it's failing.
In fact, the surprise is that it's lasted so long.

....since the bean counters get the last word
on what components go into the final product.

When a piano is played, the sustaining pedal is in constant use.
I can't help feeling potentiometres were never designed
with that kind of use in mind.

Think about a guided missile constantly being buffeted
out on the wing of an aircraft and the sensing devices in that.
It's all about specing the device for the job.

The design seems rather primitive.

....but not uncommon.