Scanner permissions

[John French]

I have a strange problem trying to use my Epson 4870 USB scanner. If I 
enter "scanimage -T -d epson:libusb:005:005" as a user, I get no scanner 
found, but if I precede the command with sudo, it does the tests and 
reports all passes.

Which suggests I don't have the necessary permissions. However, if I go 
into Users and Groups, I am (the only) member of the scanner group, and 
group members have read and write permissions. root is, of course, the 
owner.

If I try to run Xsane, I get "no devices available". I really don't want 
to run xsane as root, nor to make my user id the owner of the scanner. 
What should I do ?

As a related aside, I also notice that, although I ran "mknod 
/dev/usbscanner c 180 48" yesterday, today /dev/usbscanner has 
disappeared. Maybe this doesn't matter, since the scanner passed the 
test without it ?  If it does, how do I make it stick ?

John French