Hi Don,
No idea if this story will be of any use to you.
I noticed a second hand Wacom CTL-460k USB model in a computer exchange shop for £20.00 and asked the people in the shop whether it would work under Linux or not? did it come with drivers or not (Windows ones obviously) and got a "Uhhhhh.. dunno." answer.
"Can you show me it working on Windows then?"
"Uhhhh.. dunno" (again) They tried plugging it into a Windows laptop and not a lot happened. I don't think downloading drivers from the net was an option at this point.
"Never mind," I said, "I'll take it and see what happens." It's only £20.00 so I don't think my wife will kill me.
I plugged it in to my Mint 18.2 box and lo and behold it showed up under the System Settings, Hardware section.
Once configured, (Really weird having an absolute pointing device rather than a relative one!) it works fine. It only works over one of my two screens but that's fine. Works great in Mypaint and Freecad though I much prefer the mouse in FreeCAD.
If you've got the CTL-4100 have you tried just plugging it in? It looks like the 460k is a previous model so probably similar. Forget the free software though!
If you haven't got one, £70.00 odd is probably too big a jump to risk it not working without tinkering with drivers. Otherwise, any friends with one so you can test drive first?
Just my
Play Bonny!
p.s. Running Mint 18.3 now and all good.