Rufus: I'm not familiar with that particular model, but I do see a listing for a tuning belt for it on the Adams Manufacturing website: http://www.adamsradio.com/page9.html
Depending on the model, you might have to disassemble the tuning mechanism to install a new belt on the pulleys. An easier method is to make your own with belt material available from a number of sources, and glue the ends with crazy glue. Great Northern Radios (http://www.gn4radios.com/), Radio Daze (http://radiodaze.com/) and others carry it.
Steve