Sonicare Parts

Well my Sonicare toothbrush (the cast, in part, where the head is good) gets a nasty brown mold each month. I clean it but it always comes back. First, how to get water is there, and secondly, how can I prevent mold from developing there?

About once a week, I plunge my whole "toothbrush" handle participate in Listerine. (Not sure if I spelled that right??)
It is an antiseptic and is full of alcohol when she kills all the germs!
Plus it's okay to enter the mouth ... just not swallow.

soaked in sterilizing tablets.

Bleach and rinse well after