WORKING ON SPLICING A BELT. BELT WINDER BEING USED TO KEEP TENSION ON BELT. POWER FUSE BLEW ON WINDER CAUSING BELT TO GO SLACK REAULTING IN EMPLOYEE CATCHING HIS LEFT THUMB BETWEEN THE HOOK ON THE WINDER AND THE PULL CHAIN. RESULTED IN LEFTTHUMB INJURY. HE WAS INSTALLING BELT CLAMPS.