In reply to the Canon printers...... The offical Canon agent can be contacted at www.crc-tasktron.co.uk telephone 01483 776060 Woking Surrey I have dealt with these people who are experts in this field and am sure they will give every possible assistance.. They sometimes have second hand print heads which of course have the same consumer rights as if new.
They can give advice on removing the print heads once you have done this a few times it becomes easier.. I have a Canon ip 4500 a superb machine.