Test how the lamp socket fits in the hole in the middle of the blender base. With some blenders, the hole might already be large enough to accept the socket, in which case, you can simply use silicone glue to fix the socket to the hole.

With most blenders, you'll need to enlarge the hole. To do this, use the rotary tool to gradually and evenly grind away the sides of the hole until the light socket fits in snugly. (Don't forget to wear eye protection— the Dremel spits shrapnel.) A simple file also works, but takes much longer.