Tops Amp Removal:
There are 8 Allen head screws (10 on AT312 and MFLA) around the perimeter of the heat sink. Pre-2021 models have button-head screws that require a 3mm Allen key. Later models have socket-head bolts that require a 4mm Allen key.
Remove the fasteners. Make sure the Allen wrench is fully inserted into the socket before turning in order to prevent damage to the bolt head.
Use the PowerCON connector, provided the other end is NOT connected to an outlet, to apply gentle, steady tension pulling the amp from the cabinet.
Set the cabinet on its back, amp toward the floor. Raise one side of the cabinet about 6 inches from the floor and drop it. The shock is insignificant to the cabinet and the amp but potentially more than the adhesive can resist.
Use a broomstick to apply pressure from the inside of the cabinet, through a port or access panel. Pressure should be applied only between the power connectors.
Place a large, flat screwdriver with the flat side of the blade against the edge of the heat sink. Using the cabinet recess walls as a fulcrum, steady sideways pressure can be applied until the heat sink shifts. Remember, steady sideways pressure. It’s not generally necessary to apply upward pressure and attempting to do is can damage the finish and the wood. This is the most likely option to result in damage - be gentle.
If these solutions are not effective, Harbor Freight sells a glass-grabber suction cup that can be used to pull the amp out.
Once the amp has been separated from the cabinet, disconnect the red, black, green and white wires from the amplifier and prepare the amplifier for shipment.
DO NOT SEND POWER CABLES unless you have been instructed to do so because your issue is specifically related to the power cable.
Packaging -
Pack the amp into a cardboard box of appropriate size.
Wrap the amp in a significant amount of bubble wrap or other protective materials.
Make sure the amp cannot move inside the box before shipping.
Protect your amp from the bumps and thumps of the mailing process!