Canon ip4200 prints red as dark brown - but not always!

[TonyNapier]

If any text I wish to print includes anything in red, it is usually - but not always - printed as a muddy brown. This does not occur with photographs printed through Photoshop Elements or in the test prints produced if I run either Nozzle Clean or *Deep Nozzle Clean. I thought this might be something to do with how the printer driver interprets Word, Excel or PDF documents so I took one .docx document that had printed incorrectly, saved it as .txt and printed that: the output was colour perfect. A couple of days later I re-printed both versions to demonstrate the issue and both were output with dark muddy brown. *On the occasion I Deep Nozzzle Clean I followed by printing a number of PDFs which all included some red text: the first was colour perfect, not so the remainder! Earlier in this saga I removed the print head and cleaned it to within an inch of it's life but with no improvement.
Can anyone offer me advice as to the cause and cure of this problem?

 

[ruffin]

What brand ink?
Use Canon OEM ink only, as specified

 

[TonyNapier]

Indeed, I only use Canon OEM inks.