Today I did some sprinkler troubleshooting,
My Greenlawn valves for each zone were manufactured sometime in the 1700s and I have never cleaned them.
So, bust out the gear and open up each valve manually,
clean the bladder,
The solenoid,
check the seals,
Put back together. Be careful, don't lose a nut in the mud. They're not captive nuts.
Turns out they are actually pretty sturdy, and cleaned up well. Great!
Now they work SO well that some tube further up the line decided to let go. So now I have the pleasure of digging that thing up and learning something new.