After a year or so, though, my Silent Spinner (well, my mice's Silent Spinner, really) was starting to rattle. I figured the bearing was just cheaply made, but it turns out the problem was actually the way the two plastic pieces of the wheel snap together. I generally take them apart to clean and then snap them back together; turns out that a year of doing this has made them fit together rather loosely.
My solution was to stick a little piece of cardboard into one of the clips that holds the two halves together, like this:
I got the cardboard from one of the toilet paper tubes that I give them to play with, chew on, and browse the internet with. I'll have to change it when I clean the wheel, but at least my spinner is once again silent.
