WHILE EXCHANGING BUCKET ON BACKHOE EE WAS WATCHING FOR RETAINING PIN TO BE PUSHED TOWARD HIM. ANOTHER EE WAS SPOTTER AND 3RD WAS OPERATING COMBINATION TO PUSH RETAINING PIN OUT. WHEN THE ORDER WAS GIVEN THE PIN WAS PUSHED BUT IT CAME OUT FASTER THAN NORMAL AND WAS ABOUT TO FALL WHEN INJURED TRIED TO SUPPORT AND HOLD THE PIN WHICH CRUSHED HIS FINGER ON THE BUCKET.