Jim,
As Frances mentioned, the "site:" keyword in Google search is a very handy way to get results from just one web site. You can use it to get results from public archives at groups.io in general, or you can target it to a specific group. For example:
site:groups.io/g/GroupManagersForum "super glue"
But of course, as J noted that only works if the group has public archives.
Shal
Shal Farley