03WRX - Aquamist System 2D with FIA2 - Freqent Priming Issue

[skimobile]

My 2003 Subaru WRX had been down for several months (Oct-Feb) out in the cold with a blown tranny.
It's now back on the road but the Aquamist is cycling the rear primimg (windshield washer pump) motor quite often.
At the cars ignition setting (before the engine even is started), the priming motor energizes/cycles and the blue indicator lights.
Once the engine starts, the priming motor shuts off but usually activates again every few seconds. Sometimes when it activates it is on for several seconds at a time, up to about 5-7 seconds (the blue indicator light also activates at this time).
Even when purposely not hitting target boost to activate the system during 1/2 hour of driving, the system still keeps priming itself every few secnds. This issue repeats itself both below and above freezing temperatures. When you do hit target boost, the blue light comes on and holds until the boost level drops below the set point. Just after droping down below target boost, the priming system stays quiet for several seconds then starts priming again.
Last year the pressure switch (PN 806-157) failed and the pump ran constantly, burning up the rear priming motor in the the rear resrvior in the process. I replaced the faulty switch and the rear pump motor.
Now I'm wondering that after several months of driving and then parking for several more, if this current issue could be a sign that the pressure switch may be starting to fail again, if it is another issue, or if I am just worrying needlessly.
I've checked the lines from the rear reservior up to the System 2D motor and then onto the injector nozzle located on the intercooler pipe, several inches away from the throttle body intake, I don't see any signs of external leakage that could cause a pressure drop and require the system to re-prime itself so often. Could the High Speed Solenoid Valve (PN 806-244) be to blame?
Here's pics of the set up. Any help would be appreciated.
schematic.