still upgrading from 2.0 to 7.0

[steve%prd.co.uk@localhost (Steve Blinkhorn)]

Still upgrading from 2.0 to 7.0, I have a running system and I can
login as root at the console using the password I have set.   I can
login as an ordinary user across the network, but I cannot su from
there, and on the console if I su to an ordinary account and then try
to su from there, I gent authentication failure.

I very much suspect that this is a PAM issue of some kind but I have
little familiarity with this sort of configuration.   So far as I can
see, /etc/pam.d/su is not different from the same file on other 7.0
systems I have running.   I have checked, and su is /usr/bin/su.

I'm about to start upgrading the 3.0 system to 7.0 - this already had
a working PAM configuration, which I don't want to trash...

-- 
Steve Blinkhorn <steve%prd.co.uk@localhost>