modifications....
this is the first thing I do. I change the default switch with a new one.
In those years SPST switch were used. I change it with a DPDT even if a DPST could be enough.
Here the schematics of both types and a picture (on the left the old one, on the right the new one)
This modification improve a lot your safety working into the cabinet so I suggest to do that.
PS:
SPST = Single Pole, Single Terminal
DPDT = Double Pole, Double Terminal