Hello, William -
I hope you kept the user manual which came with the hand blender. The hand blender is probably still under warranty.
If you do have the manual, look for the information about the warranty, so the Braun company can provide you with a replacement or cover the cost of authorized repair.
That model number is for a juicer and not a tool. What you should do is take a picture of the screw and go to a hardware store etc and show them. They can recommend a tool to remove it. Lowes, Home Depot, Ace etc.