I just powered up a PID for the first time on my heat treat furnace build. The thermocouple temp display on the PID changes erratically, large swings from tens to hundreds. The PID is an Auberins SYL-2352P. Manual Here. The thermocouple is a TC-K-KLN type K high temp thermocouple for kiln. I have it wired it per the manual and double checked the settings, the polarity and connections. I also tried grounding the negative side to the enclosure per the manuals suggestions but it still jumps around erratically. Anyone have an idea as to what is causing this?