yeah mate a copper drift is a piece of solid copper rod that is used to direct force to one area the size of the diameter of the drift, like you could possibly knock it into the temp sensor reccess.... I think, but possibly the sensor will not go through that way, I can't remember on mine but I think the heat gun idea could get the metal to expand a tad and that could all be enough to loosen it enough to come out, plus when the metal area expands, the penetrating lubricant may find it's way to the concerning area and free it up