Remove the burner from the TRH (details)

Use a standard flathead screwdriver to loosen the 4-front plate screws and remove the front plate & flame/air tube assembly.

Disconnect the ignition transformer lead wire by gently grasping it with your fingers and pulling it straight out.  A slight side-to-side motion may help.  It is generally a large RED wire.

Grasp the atomizing chamber firmly and lift straight out.  This is best accomplished by pulling the top of the atomizing chamber free, and then lifting from the bottom to release the bottom O-ring seal.  The atomizing chamber is not held in by any screws or fasteners, however it may be lodged tightly against its O-rings.

Replacement atomizing chambers are shipped with protective caps over the fuel and air intake ports to keep out debris.  They must be removed prior to installation.

When installing a replacement atomizing chamber, take caution in avoiding bending the ignition electrodes (the small wire protruding from the top of the chamber).  The gap and alignment of these electrodes is critical for proper ignition.

Prior to Installing the replacement atomizing chamber, be sure to clean any debris from the inlet areas and check the inlet O-rings for proper position.  Once that is done, the atomizing chamber can be pushed straight in at which time you will feel the O-rings seat.  This is best accomplished by pushing the bottom of the atomizing chamber in first, followed by the top.

Re-install the front plate ensuring the gasket is aligned on all sides.  Be careful not to over tighten the mounting screws.  They only need to be tight enough to start to compress the rubber gasket. 

Re-install the burner, reversing the steps illustrated above. Including attaching the fuel line, power cord, and mounting pin cotter pins.