Just a followup to this older thread for those searching for this problem in the future (like I was).
A couple of posters opined that the light switch module is a sealed unit and not fixable -- this is not true.
You can easily pry off the cap piece on the very very end of the unit. This reveals some of the innards of the headlight switch part of the wand. Inside there you will see a central white plastic piece holding onto a black plastic shaft by two tabs. Pop the tabs out and you can remove the whole "twistable" part of the wand.
This will reveal that the mechanism is just a copper prongs/copper tracks arrangement. I cleaned off the tons of grease on the tracks (why would this thing need so much lubrication?) and bent the prongs down a little bit for good measure, put it back together and now it works good as new.
Save yourself $80-$160... :)
-- KEENE