After about 10 hours of working on this and basically getting nowhere, I'm 
prepared to take more radical steps.  I still can't get to Gnome desktop, 
but I don't need to use it.  In fact, I usually do not use it.  I usually 
use icewm in vnc.

What I need is a way to get to my VNC session on the local machine without 
running gdm.  Is that hard to do?

By the way, I find that these log files...

/var/log/gdm/:0-greeter.log

...grow at a rate of about 100 MB every hour or so when I'm trying to get 
gdm working.  Almost all of the output consists of repetitions of sections 
that look like this but with the process number increasing:

** (process:1888): DEBUG: Greeter session pid=1888 display=:0.0 xauthority=/var/run/gdm/auth-for-gdm-VjBW5d/database
gdm[1893]: ******************* START **********************************
gdm[1893]: [Thread debugging using libthread_db enabled]
[snip]
gdm[1893]: No symbol table info available.
gdm[1893]: A debugging session is active.
gdm[1893]:
gdm[1893]:      Inferior 1 [process 1888] will be detached.
gdm[1893]:
gdm[1893]: Quit anyway? (y or n) [answered Y; input not from terminal]

Where "[snip]" represents about 132 lines of information - I didn't want 
to clutter the list, but I'm happy to share it.  The log file contains 
many lines that have been chopped off on the right side, for example, 
sometimes instead of "Quit anyway?" it says "t anyway?"

Apparently it is trying many times to run the greeter (several times per 
second, I'd say) and it is failing.

Mike