Here are instructions copied from Vapeworld
Extreme Vaporizer Heater Cover Replacement Instructions
Extreme Vaporizer by Arizer
1.) Remove 4 rubber feet on bottom of Extreme Vaporizer base.
2.) Unscrew the 4 screws located under each rubber foot.
3.) Remove bottom base cover of the Extreme Vaporizer.
4.) Locate 2 screws only, one on either side of the circuit board (do not remove any screws that secure down the circuit boards). Remove these 2 screws that secure the stainless steel cylinder down, and remove the Extreme Vaporizer cylinder (*Note: if it is tough to remove the cylinder - wiggle the cylinder back and forth until it becomes loose and comes off - be careful not to touch the circuit board to prevent any damage).
5.) When you have the Extreme Vaporizer cylinder off you will see the ceramic heater. Remove the long cotter pin that secures the glass heater cover and remove any broken glass particles by gently blowing canned air and/or turning it upside down and gently shake it so any glass will fall out (*Note: when shaking the Extreme Vaporizer so any glass particles fall out - hold the ceramic heating element to prevent any damage).
6.) Once it is all cleaned out, place the new replacement glass heater cover in place and secure it with the long bottom cotter pin (Note: make sure the holes in the cradle and glass heater cover are lined up to prevent breaking/cracking the glass). Make sure before installing the new heater cover to put the insulation tube around the glass heater cover first.
7.) Now screw in the top 4 support screws evenly which center and support/holds the glass heater cover (*Note: do not screw in the 4 support screws too tight to prevent damage to the glass heater cover).
8.) Place the Extreme Vaporizer cylinder back on - line up the holes in the cylinder with the holes in the Extreme Vaporizer base. Position the cylinder top hole so it is centered with the top of the glass heater cover. Secure the 2 screws that hold the cylinder in place.
9.) Place/center the Extreme Vaporizer base cover back on and screw in the 4 screws and place the 4 rubber feet back on.