Thanks to everybody for your advice - I bought a pack of Staples lables - L7163 this time and tried again - I also checked my margins on Microsoft Works and made sure they matched the label sheet - printed out an A4 sheet- perfect positioning! - printed out the label sheet and lost the top half of each line leaving the bottom third of the label vacant - I then pushed the contents down a couple of lines, thereby containing [just]the top line. I'm gonna have to make do with that - it's OK, but I'm still mystified. Does the printer pick up the label sheet too quickly and position it wrongly owing to the thickness and a more 'slippery' surface? I shall try downloading Avery templates, but I can't see how that would change the printer's eccentric behaviour.

Finally worked it out! I increased and decreased the top and bottom margins on 'page set up' using one sheet of labels and using only 2 label spaces each time, one top, one bottom. I used a different strong colour each time, so was able to experiment many times. The bottom labels don't print beyond a certain depth of the label, but that's the printer - I think it must be the pressure. I didn't do a trial print-out on plain A4 - there was no point. This website was a help:- http://www.labelplanet.co.uk/printing-labels-guide.php