My trackball died after being dropped one too many times and it's not in stock anywhere in town. 3-7 business days seems impossibly long when there are public holidays scattered all over the calendar (first world problems) so in the meantime I'm using a cheap ergonomic keyboard from Ali that has an embedded trackball in the centre and it's actually not too bad.
Out of interest, what does you use? I have the Kensington expert but have been looking at the thumb operated options lately. Never had anyone to ask directly for opinions 😅
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.