You can use the 'Reset saved data' setting from the General settings screen (could be storage, but I think it's general). That will wipe everything but the registration data.
That won't help this issue, though. The problem is that podcast is publishing their feed wrong. (Warning, severely technical content ahead...)
They're publishing their content using the itunes xml namespace, as they should, but they're publishing it like this:
xmlns:itunes="http://www.itunes.com/DTDs/Podcast-1.0.dtd"
Note that DTDs and Podcast are capitalized. The official, correct namespace (
see here) is this:
xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd"
With the lowercase versions of the namespaces. This will break every podcatcher as far as I know. (You can actually test this in firefox: if you open up that feed you won't see a thumbnail, whereas any other feeds you'll see the thumbnail, even though they're putting them in the same tag).
I can add a fix to make this work (even though it's incorrect) in the next PodTrapper release, but I just wanted to let you know why there was a problem.
Ideally you could email them (The email they publish is podcasts[at]website.mlb.com ) and let them know they have an issue, but I'm not sure you'll get a response.
Hope this helps.
-Marcus