Laserjet 1320 duplex jam

[MarcG1]

Hi everyone.  My HP Laserjet 1320 is having issues with duplex printing.  The paper gets stuck at the very last moment after printing the 2nd side as shown in the photos.  I cleaned the sticky solenoid L arm as described in this thread https://h30434.www3.hp.com/t5/LaserJet-Printing/HP-1320n-Duplex-Printing-Issue/td-p/5914127 but the problem persists.  Any suggestions?

[MarcG1]

Running the "Cleaning the printer media path" procedure (I wish I had known this existed earlier) as described in the service manual seems to have fixed the issue.  In case the manual is not available to someone reading this who has the same problem, what I did was:

• Load regular copier grade paper into the tray (the manual says a transparency is preferable but I didn't have this)
• Turn the printer on
• Press and hold the green "go" button for 10 seconds
• The warning light began flashing and then stayed on
• I released the green button
• The printer processed a sheet of paper slowly

[MarcG1]

It looks like it was just a coincidence that duplex printing worked once or twice after performing the "Cleaning the printer media path" procedure, as this is still happening regularly.  Any suggestions would be much appreciated!