Assuming it is the coupler:
Take the belt off and try turning the pulley to the left and to the right,if there is any slop it'* most prolly the coupler.
The coupler can be ordered from either www.intense-racing.com
You'll also need 2 bottles of GM supercharger oil
PN 12345982 and a tube of GM red gasket maker PN 1052942
Would prolly be a good idea to start a thread in 1992 - 1999 for better exposure