I use Atlas Code 83 turnouts on the viewable area of my layout, all are powered with Atlas Under-Table Switch Machines. The throw arm shaft just barely hits the turnout throwbar and I want to extend them so I ask the question on the Model Railroad Forum and got some ideas. The one that worked seemed impossible to do. Drill a hole through the shaft of the throw arm and use music wire to move the throwbar.
This is an unmodified Atlas #65 Switch Machine.
I used small pieces of Evergreen Styrene tubing to make a drill guide as pictured below.
Next I use a small piece of K&S brass tubing as a drill bushing and a .032"/#67 drill to drill the hole through the guide.
With the guide removed I then drilled a .0465" #56 hole through the pre-drilled hole easily.
A .047"/1.20mm steel rod fits very snug in the throw arm and doesn't need glue.
The first one took two hours because I went very slow so that I wouldn't screw up a good switch machine. The second one only took 10 minutes. The steel shaft can either be pushed down from the throwbar or be cut off with end nippers.