I'm fixing the federal sign and signal 3t22 in Mapleton Utah and need some better knowledge on the solenoid dampers then what the manual says.
the story on why is, the siren was struck by lightning one day many years ago and the solenoid on the bottom damper got killed

in the end the damper ended up sucked shut.
me and some others removed the damper plate as a temporary fix but, I plan on fixing the damper.
if anyone has dimensions, pictures, patents or any other info about siren coding dampers, please post it.