The spring in the switch might just be gummed up.
Try an electrically safe lubricant and squirt some on the switch.
Work it manually. I'm sure you can adjust the travel easily too.
If you have to replace it, I'm sure it is not that complicated.
I suspected my switch was failing this past Spring - seemed to fix itself, but I'd better do the exact same thing as you are before the cold weather hits. Thanks for the reminder !
Good luck,
[EDIT}
Look for DowCorning MolyKote (or something similar at your autoparts store)
http://www.dowcorning.com/DataFiles/...b58001c899.pdf
[EDIT]