Remove the board from grip frame and reattach the front banjo. This will allow you to put air through the board while being able to pinpoint the exact area of the leaking.
Is it only leaking when the body is tightened down?
This is caused by a hose being too long
Is it leaking from the base of the solenoid?
Check the solenoid armature for any damage to the rubber base or any dirt/dust in the solenoid
Is it leaking from the top of the solenoid at the base of the T piece?
The oring may be damaged/worn out
Is it leaking from the sides of the T piece?
The hose is most likely worn out.
Are you able to upload a picture to help us identify the problem?
It sounds like a QEV was attached in the wrong spot though or the hose from the T piece on the top of the solenoid (where the front and rear banjos attach to) to the rear banjo is not put together. Does the "banjo" look identical to the front or middle banjos?