If it is the one driven by 2 AA batteries, don't even try! The inner section is held in the body by two spring clips which clip into cavities in the body under the soft plastic grip. If you feel carefully you can feel the cavities in line with the on off switch but about 3/4 inch below it. There is an identical clip/cavity on the other side. Even if you could manage to push these in - and it is not easy even after the soft plastic has been cut away - then there is the problem of sliding the drive spindle out through its toothpaste encrusted spindle.
Peritech, November 2011