> Thanks for the explanation of the trimming potentiometer. It doesn't sound like that's the problem then, as it's both
> the position and pressure that are giving false positives. Unless it somehow affects both

That's really strange and I cannot remember that we ever had this issue. The easiest thing you could try out is to replace the
TL084. It's a standard low cost and easy to find circuit. If that does not solve the problem the module has been sent in for repair.

Best wishes
Dieter Doepfer