Hoping someone can shed some light on this I am confused.....

Brought a used epson 4900, seemed to print fine on site, got home set it up. everything I print seems to print dark, run nozzle check and the green nozzle is printing black ! Am i missing something ?
Its a darker black so maybe the green is underneath ??

Any ideas anyone would be a great help as I am completely stuck on this one.

Nozzle check all clear, done power cleaning cycle, what it does print is perfect.