if you look at the body of teh switch you will see a hole. The plunger kommando refers to is visible through this hole, but there is a hitch. You can only get access to the plunger when the switch is in the on position. This requires a key.
But not to worry. You can drill a second hole over the location of the plunger. Then you can stick a small pin into the hole to depress the pluger freeing the tumbler assembly.
It is easy to locate the position to drill the new hole using the new tumbler as a guide. Align the key slot on the new tumbler with the one in the switch body. Notice where the plunger is on the new tumbler and trace a line across the switch. This will give you the location to drill the new hole.
It takes a couple of minutes to write this, a minute or less to locate and drill the new hole. When you are done you can silicone the holes to keep the water out of the switch.