How do cheap trim pots fail?

So, cheap trimmer potentiometers in the style I use on this DIY test module at the bottom right have a very short lifespan:

They’re often rated for only 100 full rotations, since they’re meant to be adjusted very rarely.

But once they do fail, how do they fail? Do they lose precision, or do they stop conducting altogether?
That’s something I can find very little info about on the web, and trying to wear out a few pots voluntarily for science would yield a very poor sample size.

(I have in mind a use case for my little experimental CMOS system where building tiny is desirable, but precision is not important.)

My guess would be carbon track wear, which can range from no contact to “jumpy” values (loss of positional accuracy in a non-linear way).

I’d bet the actual lifespan is much higher than 100 rotations too.


Looking around on Digi-Key I found some trimmers that, if I am interpreting the datasheet correctly, are tested to 1000 rotations, and have a stated life of “up to 100,000” rotations.