THREE EMPLOYEES WERE MOUNTING AN INVERTER IN AN ENCLOSURE ON THE #1 PDS RECIRCULATION PUMP. THEY WERE USING A LIFTING DEVICE AND HAD THE TOP 2 MOUNTING HOLES OF THE INVERTER THROUGH THE MOUNTI NG BOLTS. THE MOUNTING BOLTS BENT CAUSING THE DRIVE TO SLIP AND PINCH INJURED'S RIGHT THUMB BETWEEN THE INVERTER AND THE ENCLOSURE.