Found leaking valve I think What next?

AS posted previously one zone runs constantly.Dug lawn from supply line and think I found the correct valve.(If it's leaking I assume water would flowing out of after I remove the solenoid?) I opened the valve and am wondering what exactly am I supposed to be cleaning. I see a white plastic washer. Is there a screen or bonnet down further?

thanks

I will assume you checked to make sure that the manual bleeds were closed and if so the valve will probably have to be replaced. sometimes replacing the diaphram will fix the problem but I have had very little luck doing that.

Figured it out.Took valve apart and cleaned it. Works great Thanks for your advice