Hmmmm, have you tried bending the spring? (touching the two ends together?) That made it slightly easier to push for me and seemed to make better contact. (I still prefer the magnets, but they did take some trial and error to get a good activation technique too)
Edit: to be clear, you would bend the spring into a "c" shape, hold for a few seconds, and release. Don't try to put the spring on the switch post sideways . . . .
I tried it and it works, but only for a little bit. I think the spring is collapsing or at least not holding is original shape