TWO PLANT OPERATOR REPAIRMEN WERE PREPARING TO RETORQUE MOUNTING BOLTS ON REFUSE VIBRATOR MECHANISM. USING HYTORC TOOL, EMPLOYEE WAS UNDER MECHANISM HOLDING HYTORC HEAD ON NUT WHEN HE VERBALLY COMMUNICATED TO OTHER REPAIRMAN TO START HYDRAULIC POWER PACK. REPAIRMAN CONFIRMED THAT EMPLOYEE WAS READY AND THEN OPERATED SWITCH. EMPLOYEE SUFFERED A LACERATION TO TIP OF RIGHT INDEX FINGE