While installing Mint on the Lenovo Q150, I discovered that the right button on the (long disused) Logitech M305 wireless mouse wasn’t working. After replacing the batteries (always check the batteries), it still didn’t work, so I peeled the four slippery feet off the bottom, removed the screws, and confronted the interior:
Much to my surprise, the button switches had removable covers:
I put a minute drop of DeoxIT Red on a slip of paper, ran it between both pairs of contacts, removed a considerable amount of tarnish, reassembled in reverse order, and it’s all good again.
The glue on the back of the slippery feet didn’t like being peeled off, so I expect they’ll fall off at some point.
It’s much easier to drive a GUI with three functional buttons…
[Update: Long-time commenter Raj notes:
I always had problem with the middle button. I have replaced them a few times and learnt that they come with different operating pressures. The soft ones are hard to come by. I found an alternate in the PTT switches on Yaesu handies in my junk.
That’s the blocky switch to the left of the shapely wheel cutout.]
The Smell of Molten Projects in the Morning 
DeoxIT is wonderful stuff. Any idea of what’s in it?
Judging from the color, I’m guessing an extract from the blood of virgin unicorns…
Is this the stuff you use? http://www.tubeampdoctor.com/en/shop_DeoxIT_Caig_chemicals_DeoxIT_D_Series/DeoxIT_D100L_Squeeze_Tube_100_solution_2_ml_4571
Similar to that, but it used to be called DeoxIT Red and I have a lifetime supply in that bottle…
What is up with the epoxy housing of U2 — it looks like it was finished on a pancake griddle!
I really admire the way they routered that hole for the thumb wheel. Sort of Olde World craftsmanship to match the contour of the wheel assembly so closely. Nice.
BTW, isn’t Deoxit basically oxalic acid?
Those seem to be deliberate holes, but I have no idea what they lead to, down deep inside. It’s not like optical ICs need vents for back pressure…
The DeoxIT MSDS says “proprietary mixture”: your guess is as good as mine!
Plausibly holes where pins were holding the die and optics in place while the package was molded: http://electronics.stackexchange.com/questions/182365/what-are-the-holes-on-an-optical-flow-sensor-ic
Also http://www.google.com/patents/US20030034441