I purchased one of these in March from YKEY, it worked fine, I built about 6 boards with it, including some QFN and other hard to solder parts. It worked fine. Went to make another one and the unit reports "hot plate missing". I checked continuity and there is no connection on the heater. 100 ohms I presume to be a temp sensor. The heater plate is detachable, cleaned pins, nothing. I cannot find the plug in hot plate sold as a unit, only the complete system. Seems expensive for 6 boards and I am out of the 90 day warranty. Any advice? Anyone else have this trouble?