John,
I'm not surprised that Magimix won't sell sell you the screwdriver - (a) they use these screws to stop people doing their own maintenance and (b) they are not in business to sell tools...
A good tool shop will sell you a kit of driver bits - a DIY store will brobably have them too - all you need is the Hex driver handle to slip them into.
Good luck...
Peccavi, March 2009