When scanning a picture with Canon Pixma MP240 thick bands and stripes appear across the page It is now out of warranty But have only had it about 18 months?

You don't say when the bands occur. If they're in the scanned image (on screen) the problem is the scanner. If it's on the printed picture, then the problem is in the printer. Incidentally there's one for sale (re-furbished) on Amazon if you're interested (priced at £29.99) - I've included a link to the page.