Field trials over the phone with Rick seem to have solved the problem of downloading PDFs of CanalOmeters. (see previous post and comments). We achieved successes using both Google Chrome and Internet Explorer browsers. I have now put instructions on the CanalOmeters page.
After you have selected and displayed your chosen Ometer, it appears on a Google Docs page. It seems you have to use the Download Original or Print PDF options (beneath the coloured Google logo) on that page. These options really do do what it says on the tin. Other methods like right clicking the image or the link do not seem to work.
Some little issues remain. Currently some older Ometers are presented landscape, whereas as the newer ones are portrait format. Note that if you want the full size A4 version of the landscape ones, you will need to set your printer preferences to landscape. Ever since Simon showed me one he had printed up small, I prefer the smaller ones produced by the portrait format - much handier on deck.
Fingers crossed, I hope we now have a working model.