Flushmate 503 malfunction question

My daughter's resturant has the above installed. Has been working great for about two years up till now.
Water pressure seems to be adaquate. Adjacent WCs work fine.
The pressure assist system does not appear to kick in. Steps taken were as follows:
-Filled bowl with about 1.5 gal to see if there was a stoppage problem. No problem there.
-Cleaned the filter on the lower inlet valve. Was somewhat clogged but no problem now.
-Checked the air vent (duck bill) and it appears to be working.
-Removed the flush cartridge and inspected the seals which appeared to be good and re-installed according to manual.
Problem not solved. The flush cartridge STILL does not want to closed after flushing and water runs contineously into the toilet bowel.
Does anybody have experience with these pressure assist and is it normal to have a flush cartridge go bad or is it possible that the pressure regulator can go bad in the supply valve introducing a reduced pressure (to low of a pressure) to the pressure tank causing a malfunction because of low pressure.

Thanks Dave

A cartridge and regulator can wear out like any other moving part but should last several years. Depending on the serial number, the parts are under warranty for five to ten years and if it's relatively new like you said, the parts, if needed, would be covered.

The duckbill valve can also collect grit & debris that can prevent it from fully closing to retain the air and the "water bubble" trick is only an indication that it's drawing air, not retaining it, so you may want to visually inspect the duckbill, if you haven't already.

Any chance the flush-rod may be hanging up on the handle and preventing the cartridge stem from "popping up" as the valve seals? The stem will typically pop up about 1/8" or so during the flush cycle and then drop back into position as the tank reaches equilibrium. Tension on the the rod/handle interface can affect the interface between the rod/cartridge. Not really a problem in residential applications but in public restrooms, people sometimes "foot flush" and that can torque the handle a bit.

Sounds like you already covered all the basics so for best results, you may want to jot down the serial number and call the toll-free tech support number (M-F, Eastern Time business hours) on top of the tank for additional advice.

Hope this helps.

Scott
Thanks for you help.
You mentioned a couple of items I will recheck. The duckbill was clean but I cannot vouch for it retaining air although it did take in air when tested with the water.
My first thought, when I flushed, since water was not streaming out of the jet in the toilet bowl (when compared to the adjacent toilet) is that the tank was water logged (no compressed air) and working much like a tank toilet. This coupled with the fact that the water would not quite running in the bowl is that I have a either a seal problem on the flush cartridge or the duckbill check is not holding the pressure during fill.
I also noticed that the the cartridge stem did popup that little extra bit... but only one time when filling. There was clearence between the cartridge stem and the flush mechanism.
I am taking you advice and calling Flushmate (there number was on the web site) in the morning to see it the serial numbers I have are still under warranty. If so I will call the plumbing contractor that installed it knowing that there would be a service call for the labor.
If not under warranty I will go ahead and purchase the three (prv fill valve system, duck bill and a new cartridge) items and install them.
Again thanks for you help Scott.
Dave

Scott
Just a followup to let you know that I went thru all the test again since there was not much to them and determined that it was the flush cartridge, so just for grins I called Flushmate with model and serial number in hand. Surprise...surprise,...since it was under warranty, they sent me a replacement cartridge from michigan... only took 4 days to receive it. I installed it late yesterday and it worked great.
Thanks again for the tip.
Dave

Dave - glad to hear you got it resolved.