I have a Rainbird sprinkler head that has malfunctioned and is so tangled in a river birches roots that it is essentially impossible to remove or replace beyond allowing me to remove the top. Is there by chance some means that would allow me to place an extension onto the threaded body that would allow a new head on top of the existing head? Or alternatively, any way I can simply seal off this head, since otherwise it will leak a ton of water rather than spray it.