Help with Epson 4880 pro

[Awards+]

We are running two inks in our printer, sublimation ink on the left side and bulk film ink on the right. On the bulk ink side the black has went from printing fine to dropping out completely the next day. It prints black fine on the sublimation side so I would think the head is fine. You can see air in the line on the bulk side and non in any of the other lines.

[Awards+]

It's the 5th line from the bottom

71310

[signage]

I do not believe those ink print from the same channel within the head!

[Awards+]

I wonder if it's the damper?

[signage]

Check the Oring at the damper and also make sure the connection is loose. If they are all alright I would think Damper.