Take it back apart and streach the spring a bit, then reassemble. It will not get extreamly tight. Unless your spring is missing...?
Spring goes on the switch, through the hole from the back, then the chrome bezel snaps on. Push the switch against the spring. Note the nubs on the switch that coorespond to the bezel. It only goes on one way. Big hole to big nub, little hole to little nub. If the little nub is broken off (common problem) pitch it and order a new switch (unless you are really crafty and can repair it) cause it will never be tight enough. I usually hold the bezel in place and carefully push the switch into the bezel and turn the switch to snap it in place.
Note that the lock cylinder must be removed prior to any of this being done. It goes back in last.