Reverse Osmosis Constant Draining

[user 31391]

Hello, new to the forum with an old problem, I'm guessing. I have a reverse osmosis system under my sink a Whirlpool WHER25. It tends to drain constantly. Here's what I can tell you about it up to now:

• All filters are new and the RO membrane is only 6 months old
• I drained and pressurize the tank (TP-12 3.2 gallon). It fills up completely and will drain completely
• The tank fills within 4 hours but will not stop draining- It will stop occasionally by itself and, if I cut off the water supply and turn it back on, that usually stops the drainage until water is used and then it drains constantly again.
• pressure going into RO unit varies between 60 and 70 PSI, tank is pressurized to about 7 PSI empty , reads about 45 PSI full
• replaced automatic shutoff (part 7333145) and flow control (part 7333153

I'm guessing a new diaphragm kit (part 7333179) or maybe a tank but i'd like not to throw parts at this. Any suggestions?

Thanks