I do not believe the issue was due to dirty contacts. The test PC is relatively new and the physical post is much used for various other purposes - flash drives etc. - and has not shown any issues. Perhaps I should have said an issue with the usb controller. Note that a VMWare virtual machine with the scanner installed did not work on the test PC but worked fine when moved back to my main PC. No changes to the VM nor scanner configuration.
As to tigervnc… the older than ancient Pentium 4 PC has been repurposed as a data server and thus does not have a monitor. I have seen strange things when working over vnc and if the “fix” worked over vnc I am sure it would work if I connected a monitor and keyboard to the physical box.
Bottom line - the issue revolved around permissions. The account running the scanner needed to be a member of group “lp” or the permissions on the scanner had to be opened up to all with the entry in the udev rule.
Ken