I have already read a warning that trying to replace one of these torsion springs can result in injury or death, so we'll have to call someone.
The question is: to what extent are the torsion spring mechanism and the opener interrelated? It's an old All-O-Matic opener (installed by a previous owner) with no optical sensor to prevent injury to people who happen to be in the doorway when it closes (although it does reverse if it meets a physical obstruction). There is also no way of opening it just a little way (e.g., to get the newspaper) then closing it again without first opening it all the way.
So if we want to install a more modern opener soon anyway, do we still have to have this spring replaced first, or do we need to think about a whole new mechanism, perhaps of a different type?