7880 air pressure pump assy failure?

Is there anyway to diagnose a 7880 air pressure pump assy failure?

After replacing the dampers, flushing box, and cleaning assembly (capping station, wiper, motor, etc. – the entire assembly) and installing Piezoflush carts in all positions a couple of things: 1.) when I do an init fill the flush is not getting all the way to the head – it actually took 3 - 4 power cleans over an entire day and 2.) I am seeing flush after doing a nozzle on channels 1 - 4 (left ink bay) but not on channels 5 - 8 (right ink bay). I removed the tubes going into the top of the dampers on channels 5 - 8 and confirmed that ink is flowing through them (by moving the locking lever up and down. I was also able to suction ink through these lines using a syringe inserted into the bottom (i.e. where it attaches to the top of the damper) of the L-tube and was able to pull ink through the lines (as I could visibly see where the flush started and the ink ended). After re-assembling everything and doing an initial fill I am not seeing any flush flow through channels 5 - 8 (and can see air in these lines).

I am not getting any service error messages.

Let me know if photos would be helpful.

I am wondering if this could be an air pressure pump failure (or early failure)? Is there anyway to trouble shoot this assembly?

thanks!
Michael