Jens
thanks for that link, I downloaded the ZIP and have (tried) to installed it. No go yet.
I tested with vuescan and it couldn't see the Nikon. As a decades long IT person I feel (intuitively) that everything needs a driver, so I thought "bugger it" and used drivesnapshot to take my system back to before I installed my 4990 (luckilly that's just a few weeks ago).
From this state vuescan would not see it. Importantly (I think) when I plugged the Epson in, the "plug and play" bits recognized something and tried to identify and install drivers (it gave up and asked for help) I then installed the Epson software and then rebooted.
Now vuescan can see my Epson scanner (where it could not before).
Since this scanner came with no software I suspect that it is a driver issue.
thanks for the assistance