I have a couple of fermentap dial/bimetal thermometers that I want to calibrate.
There is something that should be a setscrew on the side. However the inside of the head is smooth, so I can't turn it with an allen/torx/whatever. This is by design, not because anything has been stripped.
So the question is: how do I calibrate these? Any ideas or experiences?
Ex fermentum, scientia.