What is being protected is not so much the motor, which is a very robust construction, but the rest of the deck from impact caused by the motor moving on it's springs in shipping.  Specifically, the delicate eddy-current disk, the drive-shaft, and the idler mechanism are at risk. 

 

Whether using the transit clamp or using wedges to shim, it's important that :

 A. The on-off lever is firmly set to "off".

 B. The speed control (pitch) dial is set to "+" all the way.

 

The way the original clamp works is that, with platter removed, it's tightened from above evenly on both sides so that the mass of the heavy motor is drawn upwards toward the frame.  The wedges work the same way, but care must be taken to stretch the support springs no further than is necessary to secure the motor.  A wind of tape around the outside of all four wedges will hold them in place. 

 

Packaging should take extra care that the breakable bakelite levers are protected, and that no weight or pressure bears on the spindle or motor-drive shaft.  Under-deck levers and linkage should also be protected.  No packing tape should be used directly on the enamelled upper surfaces, which may not survive the shock of 'un-taping', since the enamel may have become fragile and ready to flake when abruptly peeled tape pulls at the surface.   From there the 301 should really be double-boxed, platter cushioned and boxed separately, and placed in a sturdy double-wall cardboard shipping carton. 

 

( More often than not, the 301's friction-fit platter will have been seized in place.  Since it's sometimes a subject of some contention for the seller to remove the platter, the wedge approach can be done from below without broaching the platter removal issue.)