And Back to getting my Two Trees Sapphire Plus working

[Gambo]

If your hot end is the same as the Sapphire pro the locking screw for the thermistor is hiding up a hole accessible from next to the heater locking screw. It is an M3 like the heater locking screw. You can see it in your photo of the bottom of the heat block. incidentally be carefully tightening the heater screw the thread is very short in the heater block so strips easily, then the only solution is to drill right through the block, tread the new hole and lock it from above.Gambo