If the bristles will reach the metal, you might try a toothbrush. I use them to clean the edge connectors for the lathe and tape machines about once a year, if voltages look a little low. I also do this procedure on fuse holders, which can become resistive. Using the small paintbrush applicator, I paint a little bit of DeOxit D5 on the metal contacts. Then I gently brush them, like teeth. Then I paint some DeOxit Gold, if applicable. Once it's dried enough not to be shorting adjacent pins with liquid jumpers, I power on and usually find better voltages for many months. Be very gentle, but persistent, scrubbing this way and that, for best results with the Oral B.
- Bløn Øte