HP 6110xi Message says Paper Jam: Clear jam and then press enter. I have found no jam whatsoever, even after taking the back pannel off and the paper out as well as lifting the hinged door up. Everytime I hit the enter button, the gear makes a noise like it is spinning against the drive gear and goes back to paper jam. This is true even if I turn the machine on and off and even unplug it.

If paper is jammed, a Paper jam message will appear on the control panel display.

Follow these steps to clear the jam:

1. Gently pull any jammed paper out of the output tray or sheet feeder.
   
   
2. If the paper is stuck inside, turn off the Epson Stylus CX.
   
   
3. Open the scanner, remove the jammed paper and torn pieces, close the scanner, and turn the Epson Stylus CX back on.
   
   Note: Be sure to check the far left of the carriage area when checking for jammed paper. Paper that is jammed there may be hidden from view.

If paper jams inside the Automatic Document Feeder, clear the jam as follows:

1. Open the Automatic Document Feeder cover and remove any jammed paper.
   
   
   
   
2. If necessary, lift the document cover and remove any paper that has jammed inside.
   
   
   
   
3. Press OK to clear any messages on the display screen.

HP Officejet 7200, 7300, and 7400 Series - 'Paper Jam: Clear jam, and then press Enter' Message Displays on the Control Panel Display
Issue
During printing, the paper becomes stuck in the all-in-one and the error message 'Paper Jam: Clear jam, and then press Enter' displays on the control panel display.
Solution
Use the following instructions to clear a paper jam from the product:
Step one: Check for and remove any loose paper from the In tray
Do not try to remove jammed paper from the In tray. First remove any loose paper from the In tray to avoid worsening the jam.
CAUTION: Always try to remove jammed paper from the back of the printer first to avoid mechanical damage.
Step two: Clear the jam from the back of the printer
Follow these instructions to clear jammed paper from the back of the product. If the product is equipped with a two-sided printing accessory, skip to that section.
Remove the rear access door to clear the paper jam

1. Remove the rear access door by pressing the buttons on the side of the door and pulling it toward you.
Figure 1: Removing the rear access door
Rear access door
2. Gently pull the jammed paper out of the rollers.
WARNING: If the paper tears while removing it from the rollers, check the rollers and wheels for torn pieces of paper that might remain inside the product. If all the pieces of paper are not removed from the product, more paper jams might occur.
3. Replace the rear access door. Gently push the door into the all-in-one until it snaps firmly into place.

Remove the two-sided printing accessory to clear the paper jam

1. Remove the two-sided printing accessory by pressing in the buttons on the sides and then pulling the accessory toward you.
Figure 2: Removing the two-sided printing accessory
2. Gently remove any jammed paper.
WARNING: If the paper tears while removing it from the rollers, check the rollers and wheels for torn pieces of paper that might remain inside the accessory. If all the pieces of paper are not removed from the accessory, more paper jams might occur.
3. Press the button on top of the two-sided printing accessory to open the door.
Figure 3: Opening the two-sided printing accessory door
4. Gently pull the jammed paper out of the rollers.
5. Close the accessory door.
6. Reinstall the two-sided printing accessory.

Step three: Clear the jam from the automatic document feeder (ADF)

1. Remove the document feeder tray from the product by gently pulling it.
2. Lift the cover of the automatic document feeder by pulling it outward.
Figure 4: Lifting the cover of the automatic document feeder
Automatic document feeder (ADF) door
3. Gently pull the jammed paper out of the rollers.
WARNING: In the rare occurrence of a severe paper jam, you might need to remove the face plate from the front of the automatic document feeder and lift the pick assembly to remove torn pieces of paper from deep inside the automatic document feeder.
4. Close the cover of the automatic document feeder, and then reattach the document feeder tray.

Step four: Verify that the print carriage can move freely
Follow these steps to try to move the print carriage.
CAUTION: Do not force the print carriage to move if it is out of plain view or feels stuck. Forcing it may damage the printer.

1. With the product turned on, open the print cartridge access door. The print carriage might try to move into the access area. If so, allow it to move to that position.
2. Without turning off the product, unplug the power cord from the back of the product. Unplug the power cord from the power source. The power cord must be unplugged to allow the parts to be moved by hand and to reset the paper feed mechanism, without the risk of an electrical shock.
3. Looking in through either the print cartridge access door or the output paper tray, make sure the print cartridges are locked into the carriage and have not come loose. Also, make sure that there are no obstructions under or around the carriage to block it from moving.
4. Make sure the print carriage can move freely across the width of the product by gently pushing the carriage to the left and then to the right. Clear any obstructions found.
You may have to reach through the output paper tray to access the print carriage.
5. Close the print cartridge access door and plug the power cord back to the back of the product. Plug the power cord into the power source.
6. Press the On button to turn on the product.

Step five: Reload and test the printer
After you have removed the jammed paper, make sure the product is still functioning properly.

1. Reload the product with plain paper.
2. Peform a self-test by pressing and holding the RESUME button on the control panel until the product begins printing. A test page prints.

Step six: Service the printer
If you have completed all the steps listed above and are still experiencing a problem, service the product.

1. Remove the paper from the paper tray.
2. Press the Power button and then wait for the jam to clear.
• If the paper jam cleared, try the print job again.
• If the paper jam is not resolved, continue.
3. Remove the rear access door. Press the handle to the right, and then pull out the door.
4. Remove any paper that is inside the printer by pulling the paper out from the back of the printer.
5. Replace the rear access door.
6. If the paper jam cannot be removed from the back of the printer, raise the product cover, carefully remove the jam from the front of the product, and then lower the cover.
7. Re-load the paper in the In tray. Fanning the paper makes sure that the pages are not stuck together.
8. Press the Power button ( ) to turn on the product.
9. Open the document in the application in which it was created.
10. Click File, Print, Properties, Printing Preferences click Paper/Quality tab.
11. Verify that the type of paper specified in the Type is text box matches the type of paper being used. A paper jam might result if photo paper is specified in the Printer Properties dialog box, but plain paper is loaded in the printer.
12. Click OK to try job again.

I had a paper jam. I removed the offending sheet of paper which unfortunately tore into 4 pieces as it came out. Upon piecing the sheet of paper back together - there is a small piece missing. I've checked the printer thoroughly - nothing can be found!

Clear Carriage Jam and Press ENTER to Continue Message Displays for HP...
Above applies to your printer. Below is a video for a different HP printer but it does show some unusal places where paper can be stuck.

Fixing Carriage Jam HP Photosmart Plus All in One Printer B209a YouTube

Sounds like you have a jam. Open the back of the printer and checl for any paper large or small. If there is no paper, just opening the door and closing it may get rid of the message. All it takes is a piece of paper the diameter of a pea to send a signal that there is a paper jam. After yuou have finished close the door and push enter to let the printer know you are finished. See if this helps. I don't think it has anything to do with the ink cartridges. It sounds more like something stuck causing the jam. Be sure not to have anything like a staple attached to the paper you are printing on to. A speck of dirt could casue a jam message too.

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Were you doing duplex? take out the duplex and look in side and UNDER it

Sometimes while clearing the jam (if there was one) you may leave a bit of paper left behind which obscures a sensor causing it to think there is paper still in the paper path, or sometimes even paper dust can do it. Try a bottle of compressed air and blow the path out very well. Get a bright light (good flashlight) and very throroughly eyeball the paper path for any "foreign" objects...

Check
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00265823&cc=nz&lc=en&dlc=en&product=422000&dlc=en&lang=en

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HP PSC 1600 and 2350 Series - Paper Jam or Paper Feed Problems"

When the all-in-one detects a paper jam, the following message appears: Paper jam: Press OK to continue . The computer might display the following message: There is a paper jam (or misfeed). Clear the jam and press the Enter, Resume or OK button on the HP PSC. This document will assist in correcting paper-feed problems such as paper jamming, print slanting, and multiple pages feeding into the all-in-one. Clearing paper jams