if u don't mind, please go to http://listserv.mysmac.com/pipermail/demo-users/
On the "Downloadable Version" column: archive 19990604 is the problem I'm having now (and still do), archive 19990602 is what I will get if I run ~prefix/bin/arch <list name> whatever whatever
I got a chance to observe that the problem was there some time ago, but now I'm no longer allowed to view the URL mentioned above.
However, I can only find one place in the Mailman code where a gzipped file is being created -- and that's the one I fixed by my first patch to solve this problem (line 889 of current CVS HyperArch.py).
Neither can I find no likely chmod() calls to cause the problems you're seeing.
So, unless anyone else speaks up and tells me they have similar problems, I'm going to have to assume that the problem is specific to your system (in some way -- without having a closer look at the system from within, I'm unable to pinpoint the problem further).