Welcome to the forum.
The Vacuflush is a very easy system to maintain.
The Dometic Vacuflush 506 head
could be a problem, if the seal was leaking, but the OP reports the bowl remains full, so that potential problem could be discounted.
The VG2-12 vacuum generator
uses a piston bellows pump
, w/ four duckbill (Joker) valves to create the vacuum.
The system vacuum is detected by the vacuum switch assembly
where a diaphragm
works against a spring and the position is detected by a switch.
The "easy" way to determine if the switch is good/bad is to unscrew it from the vacuum switch assembly and then manually actuate the plunger.
If that test shows the switch to be good, then the big suspicion I would have is the duckbill (Joker) valves. Those could invert, could be installed incorrectly oriented or the fittings could be over tightened, distorting the shape, keeping them open.
Whenever I plan on vacuum generator service
w/ a functioning system, I first fill the bowl w/ water
, then run a large slug of water through to the holding tank
, until I can audibly hear the head
drain hose to be empty. I shut off the water supply after the bowl is full, so the vacuum generator drains as much as possible.
My preference is to keep these parts
scrubbed clean and properly inspected for issues to avoid / prevent problems.