Envelopes are not sealing on the SendPro MailCenter 3000

If your envelopes are not sealing or not sealing properly on your SendPro MailCenter 3000, perform the recommended maintenance operations here.
Products affected: SendPro® MailCenter 3000


Envelopes are not sealing properly.


  • The sealant bottle is not seated correctly
  • The moistener pad is dirty


If your envelope(s) are not sealing or not sealing properly, perform the recommended maintenance operations here. In order to complete these operations you will need the Moistener Replacement Kit, 2F3-F .

Unsealed envelopes

  1. Open the supplies cover located on top of the feed cover.
    Supplies cover open
  2. The envelope sealant bottle is located to the far left of the tape roll. Check to see if the sealant bottle is seated correctly. The following picture is an example of an improperly seated bottle.
    Check the sealant bottle is seated properly
  3. To re-seat the sealant bottle, lift it straight up and lower it again so that it is seated properly as shown in the following image.
    Reseat sealant bottle
  4. Close the supplies cover, then open the (a) feed and (b) print covers.
    Supplies cover closed and feed and print covers open
  5. Pull up and to the left on the (a) top release lever to expose the (b) moistener deck.
    Top release lever open
  6. Use the blue notch in the top of the moistener deck to pull the assembly up and toward you.
    Remove moistener assembly
  7. Grasp the (a) moistener pad and pull it out of the assembly. Note the location of the (b) wick. If the (c) pad contains dirt and residue and looks like the image shown here, you need to replace the moistener pad assembly.
    Remove the moistener pad and check for dirt
  8. Using two fingers, grasp and remove the wick.
    Remove the wick
  9. Locate the Moistener Replacement Kit, 2F3-F.
    Locate the moistener replacement kit
  10. Slide the new (a) moistener pad assembly back on its (b) track until it snaps into place.
    Slide moistener pad into the assembly

Make sure the moistener pad assembly is inserted correctly within the moistener deck. The following images show the proper and incorrect alignments.

Correct alignment with the moistener deck:
Moistener assembly correctly aligned

Incorrect alignment with moistener deck.
Moistener assembly incorrectly aligned

  1. Insert the new wick. Gently push it all the way down into the wick holder until it is seated properly.
    Insert the new wick
  2. Push the moistener deck assembly back into place.
    Replace the moistener assembly
  3. Close the top release lever. Make sure it snaps into place.
  4. Close the feed and print covers.
  5. Run some envelopes and verify they are sealing correctly.

UPDATED: 15 April 2024