With the current version of podPress it is unfortunately necessary save the Permalink settings after changing the slug name or activating a podPress feed in order to make URLs in a non-default Permalink scheme work.
I think this is why
has not worked.
But currently it seems that no there exists no feed with this slug name (maybe it is deactivated). I think that because if I open the feed URL written in the default Permalink scheme http://www.fasttracksites.com/?feed=seo-tips-podcast then I get the typical error message
ERROR: seo-tips-podcast is not a valid feed template.
[...](removed -podcast and its fine now).
There is no fundamental problem with the previous slug name. (removed -podcast and its fine now). seo-tips-podcast should usually work.
But I'm not sure what happens when you have categories or tags which which have comparable slug names.