Resetting gnus after emacs lockup

[geeked . up]

Hi,
 I had a working setup for newsreading with a primary nntp select
method and two secondary nntp select methods. However, I recently had
to kill emacs (with gnus active) because emacs became totally
unresponsive and locked up tight. Since then when I'm in the *Group*
buffer I'm only able to get and read new articles for groups associated
with the primary source using (g) or (M-g) and (RET). However, any
command like (M-g) or (RET)  or (SPC) on one of the groups associated
with secondary sources results in 'gnus-server-opened: Trying to
require a method that doesn't exist' in the *Messages* buffer.

Any suggestions on how to most easily re-enable reading the secondary
newsgroups again?

TIA,
Walt