Thanks for using the spoiler tag. It’s working now.
And yes, I took into account that electronic nerds’ houses are different from most others.
The storyMy Genius optical mouse was tracking poorly, even on patterned surfaces and mouse mats. I cleaned the lens and that didn’t help. So I used a knife to open the chip, which is a pinhole camera with a die that integrates the sensor, a basic image processing system, button, wheel and LED controller and a USB (or maybe also PS/2) interface. I cleaned the chip with alcohol (mainly to remove the dust that had landed on it while it was open) and reassembled the mouse to find that it made no effect on ots functionality. I ultimately found out that the focus distance was off and I fixed it by removing the rubber pads at the bottom. The chip appears to have no alphanumerical marking. Full picture of the PCB with this chip – it is slightly damaged because I needed to scrape off parts of it to allow the cover to come off; I also did this because I thought of readjusting the focus by slightly lowering the chip (by bending its legs).