Rebel1 wrote:

I went back to the place I bought the new heads. He gave me a
replacement filter screen that goes inside the housing, where the
water enters. It had a big rubber washer on it that presses against
the housing and prevents water inflow when the zone valve is closed.

Problem solved. It a standard part in the Hunter stainless steel
model.

I don't get it.

If the zone valve is closed, then a small amount of dribbling water
shouldn't be causing you grief, and it wouldn't worth my time to shlep
across town and get this part and dig down in the dirt to install it.

If your zone valve is leaking, then I'm sorry but this ain't gonna fix
it.

If it gets down to freezing in your area in the winter, then you're
gonna wish you hadn't installed that rubber thing.