I’ve been using a Kesington Expert Mouse for about 6 years now and would like to share my experience with both the device and repair. It is my favourite “mousing” device since it occupies a fixed area on my desk. Too often I’ll have piles of paperwork or hardware on my desk with no room for a regular mouse to move around. It has the right amount of controls, and a nice no frills design that fits right alongside my new favourite keyboard.
When I’m away from work people will generally bring a regular mouse and plug it in. The trackball tends to scare people for some reason, even though it is easy to translate trackpad movements to it (larger ones like the Apple Magic Trackpad).
Recently the unit I inherited from another person at work started giving me issues with the left-click. I would drag things around but it would let go and pick up something else. It was infuriating but I adjusted my “grip” and the issue went away with a bit more force. I eventually decided enough was enough, and grabbed a donor mouse to replace the failing microswitch.