; Greg Welts ( # 3 ) Active : 1997 â `` 1998 Played : custom percussion , backing vocals Performed in : Slipknot Demo After Colsefini left the band , Greg Welts was brought in to replace him on percussion and backing vocals . ; Greg Welts ( # 3 ) Active : 1997 â `` 1998 Instruments : custom percussion , backing vocals Release contributions : Slipknot demo ( 1998 ) After the departure of Colsefni , Greg Welts was recruited to fill the spot left on percussion and backing vocals .