I updated to ScanWizard 7.62, but this couldn't find the ScanMaker 8700. It actually appeared in the scanner probe but wouldn't let you click on it. Quite frustrating!
So, I did a quick search for the problem and found this article by Microtek. They've got a work-around:
It has to be done in this order for some reason. I also removed ScanWizard Pro 7 so there wouldn't be any confusion.
I also revised the tutorial on how to use the software. I'll put it on my next post