In my case the inside of the case of the toothbrush where the cover for the start button is, was worn. I cut 3 - 3/16" squares of electrical tape and placed it on top of the start switch. This filled the gap where the worn material was and enabled the switch to be activated easier. I also noticed that some moisture was inside the case of the toothbrush, so I coated the metal shaft protruding from the toothbrush, and the o ring of the cap with some water proof grease, Vaseline.