I just repaired electric toothbrush. Again, for the third time (with different toothbrushes in my family, fuck Philips).
After two years of usage rubber button lost sealing. So replace it with screw furniture cap and seal ot with thermal-shrink tube (40/20 mm). Using only home hairdryer.
Semi-related: There is new cozy computer game where you can repair consumer electronics. It is set in 2000s japan: https://store.steampowered.com/app/3812600/ReStory_Chill_Electronics_Repairs/