Thanks for your feedback and my apologies for the delay in responding, but the printer completely died on me and I was trying to resuscitate it - all to no avail. As I have had many years of good service out of it it is time to retire it to the recycling centre. Once again my thanks.
I came across this thread, along with a number of others offering similar solutions to the 'ink absorber full' after I started getting the message and a repeated green power LED followed by eight amber flashes on my Pixma iP8500 after changing an ink cartridge.
I have dismantled the printer...