I replaced the stock black impellers with dealer-supplied yellow impellers, had problems with them as discussed here.
http://www.wakeworld.com/MB/Discus/messages/65919/593303.html?1214236376 Following the advice, I ordered (and received but have not installed) the blue impellers.
Probably will do so before next weekend when I can give the blue impellers a test.
http://www.defender.com/category.jsp?path=-1|311|53460&id=809302
To order the Globe replacements, you need to know the JABSCO equivalent in your ballast pumps. For me, it was Jabsco # 6303-0001 (or -0003).