LaserJet Enterprise M604n Envelope Crushing

[WeltonEnt]

Purchased a new HP LaserJet Enterprise M604n (model E6B67A) in Jan 2017, from HP.com Store. Installed in Feb 2017. The printer is used for linen letterhead and no. 10 linen envelopes (90g) using HP 81A black toner, and for printing checks using MICR toner. The printer did not have any issues from install to July 2017.

In July 2017, the envelopes began being wrinkled/folded on one end, the end that is fed through the printer LAST. Also the end where the envelope is embossed. We've never had a problem printing these before. We have a Sharp MX3070N that prints them fine.

HP support has been VERY difficult to communicate with so I'm exploring other knowledge bases.

What I know:
1. The envelope damage is happening in the printer, regardless of where the envelope is fed through (envelope feeder or tray 1) or if it exits the back or the top.
2. The envelope damage happens regardless of which ink is in the printer (regular or MICR).
3. There is no other damage to the envelope (waves, curling, ink spots, etc.)
4. Regular weight no. 10 envelopes print without any damage.
5. The linen envelopes are made for laser printing.
6. The "high humidity" setting on the printer does not change the print results. There is no other evidence to suggest humidity is the issue (other laser printers work fine, other paper prints fine).
7. There was no change in the envelope type, weight, embossing, etc. between when they printed fine and when the wrinkling started.
8. The printer use is so minimal that the original ink we purchased is still at 100% and the maintenance kit is at 100%
9. The printer is still under the one year manufacturer's warranty, but it has been discontinued so I'm not sure what we would get if a 'replacement' was issued under warranty.

Printertechs has worked on our printers before, and has always been great. Is a replacement recommended or should I just take it in to be serviced? Has anyone experienced this? ANY help or direction is appreciated!

[ptjeff1]

It sounds like you went through a lot of good troubleshooting. Humidity was my first thought. Make sure you are setting the humidity compensation under the right paper type. Administration>general settings>print quality>adjust paper type>envelopes>Humidity. Also try the paper curl adjustment. You will need to make the same adjustment under paper type Letterhead if you are having problems with letterhead.

When you print, your computer's driver needs to be set to paper type Envelope (or letterhead if printing letterhead) in order for the printer to know that it should use the settings for that paper type. For example, if your driver is set to plain then the printer will print according to the settings for plain paper.

I looked at one of your envelopes and it looks like a bit of separation occurs between the two sides of the envelope, and when the trailing edge enters the fuser it flattens out with small creases. I'm guessing it's a combination of humidity, paper type, and the fuser. HP might give you a warranty on the fuser, that's where the crease occurs, although I don't know if it will help.
The creases aren't very noticeable, after the envelope went through the mail system I didn't even notice it.