You need a 5/64 ball end hex driver for the locking collars and motor screws.
You also need a 3/32 for the screws.
http://www.sears.com/sr/javasr/produ...t=Screwdrivers
http://www.sears.com/sr/javasr/produ...t=Screwdrivers
They work great, I bought them for my RC trucks, but never used them; so now I use them with my VEX stuff.