Printing A4 sheets on Officejet 6700 looses stuff at the edges

Following the installation my new Officejet on th December 2013, I found that some prints were missing information which should have been printed near the top and bottom edges.

I had problems with various software, but chose a LibreOffice file and its .pdf equivalent as simple cases for investigation. Just for the record, I previously printed similar files on a Canon printer without a problem. My investigations were guided by internet pages as follows:

* http://hplipopensource.com/hplip-web/tech_docs/printable_areas.html: I initially set all four margins to 3mm as that is what is indicated in the documentation. LibreOffice objected that that was too low so I increased them to 5mm. The values in the table for DJ6xxx are 3mm, but the first paragraph of the page indicates that the margin should be 4 times greater i.e. 12mm. I tried that and most of the missing print appeared - but not all of it. When I set the margins to 3mm, LibreOffice reset them to 3.2mm, so I tried setting the top and bottom to 12.8mm, but still some was missing. By trial and error I found that side margins of 3.5mm and top/bottom margins of 1.6mm printed the whole page (when I tried 1.5mm, everything except the top line was printed).
* http://hplipopensource.com/hplip-web/release_notes.html contains "Bottom margin is not printing on 8.5x13in paper size for DeskJet 2050 J510 device" in the release notes for 3.13.5 of HPLIP as a resolved issue. There are mentions of "margin clipping" being solved for previous versions. It seems there have been similar problems with HPLIP, so may be that's the cause of my current problems.

During my investigation, I noted that a new release (3.14.1) had appeared. I decided to upgrade to that version in the hope that my problem would be solved. During the upgrade, I printed a test print which was on A4 and appeared to be OK (there were rulers on all four edges which agreed with the A4 size i.e. 210x297mm. The print of the rulers allowed for a small margin, which appears to be 3mm). However, my normal prints still failed. Therefore I decided to re-install 3.14.1, carefully noting what happened. This is as follows:
* I quit from HPLIP, so that it wasn't running during the installation.
* In a terminal, I ran "sh hplip-3.14.1.run" (which I had previously downloaded). During this run:
  + I accepted automatic installation (a).
  + I requested "remove and install" (i).
  + I selected the option to remove the USB from the printer and restore it (p).
  + I re-plugged the printer when instructed.
* A window appeared called "HP Device Manager - Setup". I selected USB connectivity. Then on step 3 of 3 I ticked the option "Send test page to printer". The A4 test page was printed and was correct as described above.
* Installation was then complete and so I started "HP Device Manager". I took the following actions:
  + Select "HP Officejet 6700 (printer).
  + I selected "Actions" and "Print test page". A test page was printed which claimed a Page Size of 215.9x279.4mm. It printed on my A4 paper with no left margin such that 3mm seemed to be off each edge of the page. There was a margin of about 20mm at the bottom of the page - again corresponding to the difference between A4 and letter.
  + To get the print, I had to select the "Printer control" tab and click "Start printer".
  + I then selected the "Print settings" tab and clicked "General". The media size was set to letter (8.5x11.0 in), so I changed it to A4 (210x297mm).
  + I selected "Actions" and "Print test page". An A4 test page was printed, which was identical to the previous one except that the bottom was blank i.e. the bottom ruler was missing. The size of the blank was about 1.5cm. I scanned the print back in and it is attached as file hpscan005.pdf.

It appears that the error is introduced at the end of the installation process when the default media size is set to letter.