Hey tparganos, Just remove the adapter, and slide the
batteries into the tube and push up. The switch may take a minute to come out, but it will pop out (be careful because it's in a few pieces, and you don't want to lose any!)
Then you can assemble the new switch and slide it in
through the top (where the adapter screws on). Screw on the adapter, insert the
batteries, and you're all set!