1) Set the temperature to 240 degrees Celsius
2) Raise the hot end so that the nozzle is at least 3″ above the bed
3) Use needle nose pliers to grip the peek tube above the heater block (to avoid inadvertently turning the heating block and ruining the thermistor and heater wires)
4) While gripping the peek, use a 13mm wrench to remove the nozzle from the hotend.
5) Turn the hot end temperature OFF
6) After the nozzle has cooled, use an exacto knife or razor blade to trim the bottom of the threaded rod to clean off excess plastic.
7) As with above, grip the peek again to ensure the heater block does not turn.
8) With a clean threaded rod and a clean new nozzle, carefully thread the new nozzle onto the threaded rod
9) VERY IMPORTANT – make sure that the interior of the nozzle seats against the threaded rod (for a proper seal) AND that the nozzle seats against the heater block (to ensure adequate heat transfer). It may be necessary to slightly rotate the peek and threaded rod to make sure both conditions are met.
10) Double check that the thermistor and heater wires have not been comprised.