Yeah, soldering is probably your best option now. But on the plus side soldering it will give you an excellent electrical connection, I may do that to mine but right now I'm working on electrically bypassing the spring, I want to keep a spring in there for safety to provide the battery physical protection against drops.
If it were me soldering it I would disassemble the switch, remove the chrome on the switch housing threads at the solder point (you don't need to remove the chrome from all of the threads) , use a small clamp to hold the switch housing snug into the tube then solder it. Don't forget to clean out the small hole the switch pin slides before you re-assemble the switch and if you have some noalox apply some to the switch pin and inside the small hole it slides in, that area is an electrical contact point. Make sure to use silver solder (better) or electronics solder, not plumbing solder. Just a heads-up, I don't know how much soldering experience you have.