the gas water heater, which is 11 yrs. old, is constantly bypassing from the overtemp/overpress valve. I have replaced the valve, drained and refilled the tank and replaced the thermocouple.It's not much,just a trickle. If you put press on the valve stem/lever it stops, but as soon as you release it starts again. Water temp is set at the A setting ( Hot,A,B, Very hot) The burner is not constantly on, and there is plenty of hot water. No leaks noted. Is it time to "bite the bullet" and get a new one,or is there a fix ?