[rheavn]

There is a 1/4" black air line that goes from your 12V air pump directly to the toilet flush valve.  Isolate that line by stubbing it off at the flush handle and insert a leak down tool on the air line to the toilet after the regulator.  That is the first place to start.  From the flush handle air is then provided to the air/sequence valve thru the green air line.  When you activate the flush valve the air should move from the green air line to the blue air line and then on to the air/sequence valve.    This description is for a coach with a 12V air pump, which I believe Bill has.

The air sequence valve can be removed without removing the toilet.