* one tiny bit of kneadable eraser
* some pencil lead shavings (from a 2mm lead rather than a regular pencil, so that there was no wood)

kneaded together for a while, applied with a toothpick over an #SMDjumper

profit!

no more cleaning a jumper that has been written over with pencil every time I try to update the firmware on my #espruinoPico

http://www.espruino.com/Pico#advanced-reflashing

disclaimer: wash your hands after kneading the eraser and before touching sensitive electronics, as they may be more conductive than usual :D