THE EE WAS USING A HYDRAULIC JACK AND SPACERS TO SPREAD APART THE PLATES ON THE P/H CRANE BUCKET. THE EE WAS IN THE PROCESS OF ALIGNING THE PIN. WHILE IN THE PROCESS OF SPREADING THE PLATES TH E EE RELEASED THE PRESSURE ON THE HYDRAULIC JACK AT THE SAME TIME UNAWARE OF HIS HAND PLACEMENT/POSITION, WHICH RESULTED IN A SMASHED LEFT THUMB.