Yep, one month after the warranty was up on my G7 mouse it started randomly double clicking making it almost unusable. The good news is I have seen this problem before in my Logitech MouseMan Wheel which is going on (7 years). To fix it just open up the mouse and clean out all the junk that has accumulated. Here are the steps to follow:
1. Remove the skid pads on the bottom of the mouse. Do this really carefully if your going to try and reuse them. I had some Rantopad replacement skid handy so i just ripped mine off by hand (ruining them forever).
2. You can now see 3 of the screws to be removed and will find the fourth under the serial number sticker. Unscrew them!
3. The base will then come easily away from the shell and its buttons. It should almost fall out, if it doesn’t check you havent missed a screw.
4. You will now see all the little micro switches on the board of the base. Clean them! use a can of air if you have it or a (clean) paintbrush.
5. Before you put the shell back on, plug it in/turn it on and check it works. (If not clean more, you might need to open the micro switch to clean it – but be careful they will break real easy – also see double update)
6. Replace shell and 4 screws.
7. Enjoy using your mouse again (Without going crazy from the random double click).
UPDATE: After about 2-3 weeks my mouse has started to double click again (all that gaming must have done more damage than I thought). I don’t really like the ergonomics of the G7 so I went and got a new mouse.
DOUBLE UPDATE: It turns out the other reason the clickers stop working is that the leaf spring in the microswitch wears out. You can fix them by carefully opening the mouse and opening up the microswitch for the offending button. Then follow these instructional diagrams on overclock.net to reshape the spring. Note it is quite small and fidely! so have a magnifying glass and tweazers handy.