I have a Wacom CTE-640 and cannot get it to run properly/find a driver for it I have a Wacom Graphire 4 CTE-640, silver. It reacts as though the pen is always down, no matter how I try to use it. The area responds, but I have to lift my hand completely for the pen to stop. 

I am running Mac OS X El Capitan on a MacBook Pro.
I have the same Graphire 4 and MacOS Mojave 10.14.5. The latest official Wacom Driver PenTablet 5.3.3-3 won't install anymore (it thinks that you have an older OS than 10.6).

SOLUTION: I tried all previous drivers until I found the most recent one that works. So the actual latest PenTablet driver that works with MacOS Mojave is the 5.3.0-3 that you can download from here: https://www.wacom.com/en-us/support/graphire-support

Hope this helps!