Thank you so much for all your help.
I do apologise for the delay in replying, and in sending feedback: I have been continuously busy until now.
1) Yes, you are right. At last I have learnt about cleaning (nozzles needed it too). I think one cartridge may have caused a problem.
2) I always use compatible inks, so there must be some other reason for the 'wiping off'.
The paper should have been OK. However, the Canon Selphy gloss paper and the Epson semi-gloss did not work - everything rubbed off. But the HP gloss paper was fine. This is a mystery, as the (excellent)specialist stationer assured me that all these papers would be perfectly OK for the Pixma printer.
May I just ask what paper you would recommend for the Pixma: the same paper for any Pixma model?
(a) 'Semi-gloss' not in the paper selection offered when printing; should I select 'gloss' or 'matt'? Maybe Canon doesn't do a semi-gloss paper.
(b) For gloss, should one choose 'Glossy photo paper' or 'Photo paper plus glossy' [or similar description]
3) Last question (I hope!).
A small amount is lost from one long side of the picture when printing, which spoils the composition. Any solution?
With many thanks (I will complete your rating when we finish!)