Question
I have an older HyrdroRain residential sprinkler valve which has failed. The valve controls city water to an indexing valve.  I'm not sure of the valve model
number since HydroRain doesn't show but only one on their website. My valve is the original in the house since about 1975.

I first noticed no water from the indexing valve to any zones.  I checked the indexing valve, it's working fine (not sticking).

I disconnected the indexing valve from the control valve (so I could watch the water as it exited the valve) and manually tripped the timer.  The solenoid actuates and
water comes out of the valve but not under good pressure.  While the solenoid was actuated, I turned the manual bleed screw open. The water pressure and flow
out of the valve  increased but water also started shooting out of the bleed screw hole.  The more I opened the bleed, the higher the water pressure out of the valve and out of
the bleed screw hole.

I turned the timer to OFF.  The solenoid closed.  I opened only the bleed screw. Water came out of  the valve but not under good pressure.  Water also shot out of the bleed screw hole. I screwed the bleed screw back in.

To check one last thing, I started unscrewinng the solenoid to check for dirt under the plunger but water immediately started coming out of the little hole (on the side) under
the solenoid.  Is this supposed to happen?

Does it sound like the diaphram ruptured or is leaking?

Answer
Yes, is is normal for water to come out of the bleed and solenoid holes.  It could be your diaphragm, but these usually cause the valve to "weep" when they are damaged, not loose pressure.  Try adjusting the valve by opening it all the way, then close it all the way counting the turns.  Then open it back up halfway.  If this doesnt work, open up the valve and check all the components, the diaphragm and all the ports (holes) in the valve.  Replace if necessary.