I've just experienced a problem with my temperature controller, a Cal 9400, and I have helped a friend with a few Cal 9500P with the sameproblem from time to time, basically sporadic behaviour and erroneous temperature readings or thermocouple failure indication. I know the problem is related to the classic problem of solder or tin plated contacts oxidising as I was aware that the guts of these controllers can be pulled from the panel mount by design to allow hot swapping such as when one goes down in a large bank as in an extruder line, it saves having to access the back of the board and removing and replacing wires when the electronics can be easily changed from the front. I just pulled mine and put it back and it's going correctly again as that action wipes the contact surface. Now I'm wondering if there is some suitable contact sealant or protective coating that I can apply to the contacts to prevent this happening again, the environment isn't hot or damp in my case but this problem comes up from time to time, my friend now pulls her's as part of the yearly workshop service. I have seen dielectric grease which seems like it might do the job but it needs to be something which won't effect the low currents in the thermocouple. Any suggestions would be appreciated. BTW I know of another kiln that is suffering the same sort of issue with one thermocouple reading low and tightening the screws helped for a few weeks but it's back but I haven't been able to check as it was being used and the 2nd thermocouple seemed OK, in that kiln the thermocouple connection is next to the case so will get hot in use so if anything is available then maybe 100C capability or higher would be good for the 2nd application.