At the end of a set of labels, my 400 jammed so I had to take off the front section to clear the jam. When I loaded new Dymo labels, it now doesn't print. Not sure if when I took off the front section of the label printer, something got imapcted. Connections are good but nothing prints now.

See here for detailed instructions on how to remove a label that has jammed inside a dymo labelwriter:

How to remove jammed label from Dymo Labelwriter

See here for detailed instructions on how to remove a label that has jammed inside a dymo labelwriter:

How to remove jammed label from Dymo Labelwriter

Disconnect both cables. Detach the front panel. Lift the paper guide (on the right). Clear the jam. Assemble the printer and run a cleaning card through it (a business card moistened with hand sanitiser will also do).

^CM

There are a few common reasons this is problem can exist.

1.) the incorrect template is used when creating the label

2.) the labels are installed incorrectly - the labels must be loaded and pushed against the left side of the printer and lid closed when printing to ensure the labels don't "wander" out of the sensor's view.

3.) the label sensor is covered by some debris - sometimes a label jam can cause a piece of label to become stuck on the underside of the sensor thus blocking its view.

4.) The labels are defective - if you have another roll of the same size, try it to see if it has the samme issue.

There are a few common reasons this is problem can exist.

1.) the incorrect template is used when creating the label

2.) the labels are installed incorrectly - the labels must be loaded and pushed against the left side of the printer and lid closed when printing to ensure the labels don't "wander" out of the sensor's view.

3.) the label sensor is covered by some debris - sometimes a label jam can cause a piece of label to become stuck on the underside of the sensor thus blocking its view. Use quality Dymo labels.

4.) The labels are defective - if you have another roll of the same size, try it to see if it has the samme issue.

You probably didn't damage it, it sounds like you may have knocked loose the thermal printing portion (which is the most important part). There is no easy way for you to repair this but Dymo will usually do it for free under warranty. Their phone number is:
(203) 588-2500

When loading the label roll..place it along the left edge then press to button on front of the label printer once and dymo will **** it in. Now it's ready to print labels. Be sure to unplug the printer and plug it back in to avoid the common "printing error" message from windows.

I just fixed my coworker's Dymo, which had the same problem. I hope this helps: if you've ever fed it labels in the wrong direction (upside down), you may have jammed it and left a piece of a label glued to one or more of the sensors that let the labelmaker know it's finished printing a label.

1. Disconnect your labelmaker
2. Disconnect/remove any unused labels and set them aside.
3. Remove the face plate (with the DYMO LabelWriter 400 logo)
4. Lift the gray plastic lip (labels go under this) and make sure there are no pieces of paper/labels in there.
Once I removed a piece of an old label and put the LabelWriter back together it started working well again.

Use a DYMO Label/Writer Cleaning Card #60622. One should have come with your printer. Just remove the labels, run this cleaning pad through a few times, insert the labels, and print.

If you've tried installing the latest drivers and the problem persists it sounds like you have a lemon. The printers have a 2 yr warranty, so I would contact the retailer you purchased from and replace the printer. If your labels are jamming. Try the compatible File Labels available at LabelValue.com. They have both the Dymo 30327 and Dymo 30277 labels in a compatible version.