Epson 9800 air pockets on Ink tubes

I left my fine functioning Epson 9800 pro, sat unattended, for a long time.
Most ink cartridges are “ SMS” exp 2018.
I am trying to get it back to work. The first print i did , when it turned on; printed mainly 2 colors : Light magenta & light grey.
Printer functions seem to operate normal; so far, I’ve replaced 4 cartridges with brand new Epson ink .
I’ve noticed some of the ink tubes (LC, LK), have air in them.( long air pockets ( 1 ft) I did some Paper towel soaks under the head carriage, an Init Fill; many nozzle cleans; But results did not improve.
It prints a faint light grey image with gaps of white horizontal lines.Nozzle print tests show no image.

What will be the right steps towards a repair plan of action?

Most likely you need to replace the dampers. These are filters (air and ink combined) and they are the things that will go even before the head.

If you replace the dampers and do a full flush of the printer you should be ok.