Hi TCR.
To change any chip(s) you first MUST be sure the power is off the machine. (I pull the plug myself to make absolutely sure.)
Remove the MPU carrier and place it on a flat solid surface so it doesn't move or rock.
Before you touch any chips or circuits on the board, touch the metal carrier to ground any static electricity that may be present.
Using a chip extraction tool, remove the present chip [ONE AT A TIME ] from the socket. Take careful notice of the NOTCH on the current chip and orient your new chip in the SAME direction.
Place the new chip in the socket, with the notch pointing in the correct position, and slowly and carefully make sure that ALL the pins are in the socket.
Press down on the middle of the chip and seat the chip fully [size=78%]into the socket. You may have to press each end of the chip to fully seat the chip.[/size]
Check that ALL the pins are still fully in the socket. If all is well, go on to the next chip following the same pattern.
When all chip(s) have been successfully changed, put the carrier back into the machine. Press firmly on the carrier to be sure you have it fully seated.
Power up and check your results.
Hope this helps.
Doc.