I was using a Kensington Profit vertical wireless trackball (the one with the red ball) and that’s what broke. I’m replacing it with a Logitech MX Ergo, which is what I had before trying the Kensington. Between the two, the logitech feels much smoother and is charged via cable, so there are no extra batteries to keep purchasing.

I have a wired kensington expert as well and definitely prefer the ball under the thumb instead of in the middle. I tried playing solitaire with the expert yesterday and it just wasn’t a natural fit for the repetitive movements or drag and drop.

I much, much prefer either type of trackball to any kind of mouse, since they sit in one spot and are much easier to manage when you’re sitting on a carpeted floor - you don’t need a clear amount of flat space to use one.