I lightly torch the coil before fixing it on. Then its much quicker to get it firing evenly!!I find I had terrible trouble with contact NiFe48 coils, getting the hot spots out. You really have to work the coil, dry firing it out of TC mode to glow the coil, compressing it with ceramic tweezers, and there are still hotspots, so then you have to strum the coil. Eventually it will glow nice and even from inside out. At this stage, cool the coil down to room temp, run it under cold water, so you can do your initial cold resistance calibration. Once done you should be alright.