I had mentioned that my forward vacu flush unit was cycling on and off too frequently. The aft unit is perfect and holds vacuum for weeks at a time when away from the boat. I saw a pin hole in a hose, and also noticed that the duck bill adaptors ere missing, only allowing for one duck bill on each side. I bought the rebuild kit, new bellows, duck bills, adaptors and new nipples and o rings. I installed it all today along with the hose from the pump to the Y valve. Since I was adding the adaptors, I had to move the pump forward a few inches to accommodate them and cut some of the tank to pump hose off so all would fit. So I tested the unit.....yep, still coming on and cycling too often, say every 20 minutes. It flushes fine, and holds water in the bowl. I must point out that the PO had a stripped screw that hods the pump top to the housing. I was thinking of drilling out and tapping with a 3/16” machine screw or seeing is I can find the next size up self tapping screw to get more bite. OH yes, and a Hail Mary as I put it in. Silicone grease was used on all o rings also.

I am thinking TWO issues perhaps :
1) Can the fittings be tightened too tight for the duck bill valves? I placed each vale perpendicular to the other one.

2) I see that the angle of the hose to the Y valve is at a tough angle. Almost like a strain on the fittings.

I have ordered a 45 degree fitting to reduce the angle, and also a sweeping 90 degree fitting to ease any stress on that may preclude a good seal.

Where else may I have overlooked?