i've been running my penguin biowheel 350b for a couple months now with polyester batting wrapped on the front of the sponge, and have no issues at all with the wheels not turning. have changed out the floss once in that time if i recall correctly. perhaps you need to give your biowheels a good vigorous dunking in a bucket of tank water to get some gunk off? and use a wet pipecleaner to clean in and around the little notches where the wheels connect to the filter. that's what i do on filter maintenance day (for this hob, about once every 2 months) and i never have a problem.
also sounds like you have too much media in the filter box itself. these cartridge style filters aren't designed to push water through a whole bunch of media like the aquaclear filters are, so a piece of sponge about twice as wide as your average cartridge is what i recommend.