HP Scanjet G4050 & iMac Mojave

Am trying to get my HP Scanjet G4050 up and running on my new iMac (Mojave 10.14.6). Neither the Image Capture app nor HP's Easy Start seem to be able to connect to the scanner.

The scanner *does* work OK on my older iMac, using the Image Capture app. (That is a much older iMac, running OSX 10.8.5).

I downloaded and installed what I believe is the latest HP driver for this Mojave, from support.hp.com/us-en/drivers/selfservice/hp-scanjet-g4050-photo-scanner/3236371 . I get as far as the "Test Your Scanner" panel in Easy Start, but when I attempt to Scan Test Page it (eventually) tells me "unable to communicate with the device".

Trying Image Capture app instead, it just says "waiting for scanner". It does have "HP Scanjet G4050" in the list of devices, and it is selected.

About this Mac : System Report : USB shows the scanner is on the USB 3.1 Bus.

I am running all this as a non-admin (during the driver install I had to authenticate as an admin). Also tried doing Scan Test Page as an admin, with the same (non) results.

There's a similar problem reported in discussions.apple.com/thread/250229182 , but I don't see any resolution there.

Thanks for any help.