Things to check:
Is layout set up in list view or form view? (form view would give you one record per page instead of all records from your found set that "fit" per page as you do in list view.)
Did you modify the size of any layout parts, maybe by accident after pasting/moving something and then getting a dialog asking you if you want to make the layout part larger?
If there's any chance of that, try creating this layout from the start using the new layout wizard and specifying your avery number. (You can do this from "scratch" by starting with a blank layout and specifying all the layout options your self, but the wizard saves fiddling with a lot of details.
Also, make sure that the correct page size and printer is specified in printer setup (page setup on macs), then enter preview mode to see if your labels are appearing correctly.
Thnk you for taking me through this. It made rebuild from scratch and check everything and of course it was the most basic of errors - the wrong Avery template (out by one digit!).
Thank you for your time and help.