Hi
Very good information in this thread.
I have a JT6040 that I bought second hand, a well used unit without any extras, but it does it's job.
Now however it has started to complain about ERR3, sporadically. So apparently there's a glitch in the connection somewhere, or the thermocouple is about to give up. Could be anywhere of course, but I guess the heating element is the place to start looking.
I noticed the cost of a replacement heating element is around €300 now. So not an option for me.
I think I have a bunch of K-Type thermocouplers with a USB-Temperature instrument, but in best case it is just a glitchy wire. I guess disassembly of the heating element is up next.
If anyone have any specific info or recommendations in addition to the info in the thread, please shout out