Bn 20 white ink hardware issue?

[dweavers]

My white ink is draining backwards down the lines,
I have replaced captop with OEM part, drew ink to the head immediately but overnight the ink line was empty, replaced with a new OEM white cartridge, and again ink went straight to the head, but once again overnight was empty, I assume it's draining backwards? but that's not confirmed.
Checked this morning and lines were empty, but machine started its normal maintenance cleaning and saw the white ink shoot straight to the head.
No other colours are behaving in this manner.
What an the cause be?

 

[cornholio]

How old is the printer? Could be something with the circulation pump.

 

[dweavers]

Would say around 6 + years old, will investigate pump further thank you

 

[dweavers]

From what I have been reading a bad valve in the damper will cause the ink line to loose pressure and flow back into the cartridge, so I think this may be the issue here?