Stopped working in about three months is there any warranty on these

Has it occurred to you to contact Orbit? Mine has worked for years without any issues.

How does one adjust the length of the stream of water? Not the radius - the length? Thanks !

On the upper most far front of the assembly (the silver piece) with a set screw in it, by moving that up or down will adjust the radius of the flow. By pushing it down decreases the radius and by moving it up will increase the radius. You may have to loosen the set screw a tiny bit to allow it to move but you will need to tighten it back up for it to hold it's position. The silver flap like piece actually breaks up the flow of water to reduce the radius flow and you get more of a spray rather than a stream of water.

What is the pitch of spray?

The pitch can be varied by a variable "hooding" mechanism that is over the actual water spraying nozzle. You can lift it completely out of the stream of water for the greatest distance or you can hood the stream and point the water downward