Epson ET-14000 not printing Yellow

[chet]

My Sub printer has just stopped printing yellow, I've ran the head cleaner a few time with the hope that would work... I did not.
I now think that I need to carry out an Ink flush It says that it will use a lot of ink but it does not say where this ink goes, are there any guides that could help me out please.

Thanks

[chet]

Took the bull by the horns and just did a ink flush and crossed my fingers, no ink on my shag-pile and the yellow is printing again