I finally got the HP6350 scanner on my pmax box working. Many thanks
to all the people who helped on this. Oliver Rauch, the author of
sane, explained to me the environment settings for debugging, that
immediately showed that the problem was due to a couple of drivers.
In the file /usr/pkg/etc/sane.d/dll.conf I just commented out two
entries: `as6e' and `plustek' (bugs?). If anybody needs more info
I'll be glad to supply it.

Dan