My elderly but excellent i9950 has developed a problem - it looks as though the magenta ink is not passing through the head nozzle, so colours are wrong. The test prints show no magenta block. Tried all the usual cleaning processes (apart from physically going at magenta "ring" on the print head) but no use. Canon say tough, out of date, no spare parts, buy a new printer... Grateful for any advice before doing so. Many thanks.