When my ancient Logitech G500 mouse stopped working properly, I followed these helpful instructions to bring it back to life. Now I know more than I ever wanted to know about the mechanics inside the Omron D2FC-F-7N microswitch.
Here’s a short video I made showing how it should work:
This is a photo of a working switch:
The following switches will not work as the leaf spring is not positioned correctly in one of the notches:
I recommend opening the switch from this side (compare label on your switch for orientation):
Finally, a photo with my finger shows why these are called microswitches (actually Omron uses the term “Ultra Sub Miniature Basic Switch”):
Disclaimer: If your mouse has been in use for several years, you should seriously consider buying a replacement switch. I believe you could desolder the switch from the top by cutting it into pieces first (the plastic is rather soft). Replacements don’t seem to be available from electronic components distributors but are sold on Amazon.com (affiliate link).
I was only able to repair my mouse because I had another broken one from which I stole a leaf spring (from the less-used right switch). The original spring of the left switch in my mouse was badly deformed. Unfortunately I can’t show you any pictures because it flew away when I tried to bend it.