Search google for something like "pondmaster mag drive" instead of Danner and you'll find a lot more results and information. All the pond/fountain guys seem to refer to the pumps by their more common Pondmaster name than the Danner label, even though they are the same thing.
To save you the hassle, here are a few places that sell replacement parts for Danner/Pondmaster pumps such as O-rings, impeller housings, and impeller assemblies:
http://www.westernpond.com/submersible_pumps.htm
http://www2.shopping.com/xDN-Garden-...ds_com-~all-kw
http://gallery.bcentral.com/GID13960...rs.aspx?page=1
http://www.azponds.com/subpumps.htm