How to change microswitches (left/right "mouse button") on Logitech G700?

Okay I got it! The mouse is working just fine.

The 14 points on #3 are "Rectangular Connectors/Headers/Pins".

I had to unsolder them one by one. After that I was able to lift the board.

Here is how it looks like underneath the first board:

After that you just have to unsolder the three points from the microswitch you want to change. Put it back together and you're good.

There is no need to disassemble it quite that much, or actually even to replace the switch. What happens is that inside the switch is a piece of metal that acts like a spring and it loses it's tension after a while causing the dreaded unintended doubleclicks. You can just open the switch, take out the metal spring, firm it back up by bending or straightening as appropriate depending on the action of your particular switch and put it back together.

I've done this a few times now, and it always lasts at LEAST a year before the bad behaviour returns. Probably more but I haven't really kept track.

Now, if only the back button was as easily fixed... haven't found out how to do that yet =/