Bend a paperclip and place it onto the belt to add some tension to the belt, that also provides spring
Get a paperclip, and open it up.
Make a \'v\' shape that is very open, and bend the ends to create a \'u\' at each end.
Slip the \'u\' over the belt, and use the midle of the paperclip to push out and create the spring in the belt.
See pics for details, they speak better than words!
for a vid, check out http://www.youtube.com/watch?v=LCiw007_duA