I am honestly not sure how much the biowheel actually does to help filter the water. It's supposedly to help with Biological filtration as it is supposed to houses beneficial bacteria. ANY surface in your filter and your tank will house beneficial bacteria (BB), so I am not sure that the wheel or whether or not it turns is even important. I have heard that many hobbyists actually remove the biowheels from the Marineland Penguin and Emperor Filters, and add their own filter media to the filters... such as ceramic rings, sponges, etc.. which likely do a better job housing BB than a turning wheel does. As long has you have some sort of media in your filter that BB can grow on you should be fine if the wheel is not turning. I have the Penguin 350 that has Two biowheels. I left them in because I figured they wouldn't hurt, but I also added a layer of sponge, and ceramic ball filter media, as well as pieces of lava rock to my filter. Lava rock and sponge are excellent media for BB as they are full of holes and pores that BB can grow in/on. One of my wheels doesn't turn as much as the other one does because I have more filter media on that side of the filter blocking the flow some, but I am not concerned by that because I know that the sponge, filter media and lava rock are doing far more than the wheel is to grow BB. So I wouldn't worry too much about your wheel not spinning, as long as you have other material/media for your BB to grow on.
