If the moistener tank is full and your envelopes are not sealing properly, clean the moistener brush and wick.
Grasp the moistener brush assembly and depress the moistener release button as shown here.
The release button is located on the underside of the moistener assembly.
While continuing to depress the release button, slide the moistener brush assembly straight out toward you.
Separate the shield from the wick. Clean the wick in plain water and rinse thoroughly. Blot excess water from the wick.
Remove the moistener brush by sliding it out of the moistener brush assembly.
You may need to exert some pressure to remove the brush.
Clean the brush by running it under plain water. Blot the excess water from the brush after rinsing it. Replace the brush if you cannot clean it thoroughly.
Slide the moistener tank back into the machine, followed by the moistener brush assembly
You should hear the moistener brush assembly click into place.
UPDATED: February 24, 2021