Double banding on Canon Pixma IP4000

Has anyone experienced the following?

On colour nozzle checks on my Canon Pixma IP4000 I have two cyan bands reflected.

However both bands are split distinctly between a light and darker cyan. The bands are solid. The banding is reflected of course in the prints.

I have washed out the printer heads under a warm running tap, left it overnight in a solution of 96% ethanol, blown out with compressed air can and deep cleaned in the printer software. I have still the exact same problem.

Has my cyan head turned up its toes or should I buy some head cleaner and try that.

I love my printer but don't know if I must replace it. The heads vary from £85 up so their replacement is not economic.

I have been using some third party ink - not as good or reliable as Canon's but being on a pension the cost is difficult.