We have a very old in ground sprinkler system, which for the most part has been working fine. I have replaced a few sprinkler heads, etc over the years. A couple of days ago I replaced a head on Zone 2 and ever since then when Z1 or Z2 are active, they both come on. Z3 operates fine. We only have 3 zones. Of course with both zones on the water pressure is low so neither zone is operating with full pressure. I have checked the controller, the solenoids, checked for a short between wires for z1 and z2 and made sure that there was no voltage on any other terminal other than the one Active. I'm thinking the only thing left is maybe a leak? Anything else I can check? I won't be able to do any more trouble shooting for a couple of weeks but it would be nice to have a direction to go when I get back home.