I always have a couple of old toothbrushes in my toolbox; they have the proverbial thousand-and-one uses. I've even used one to help de-gunk a stuck bolt -- but not in free-fall.
ABC News reports on how astronauts on the ISS freed a stuck bolt on a replacement electrical switching unit: Space Station Saved by a Toothbrush?
What to do if there is no hardware store in the neighborhood and the next supply ship is months away? Build it yourself -- so they attached a simple toothbrush to a metal pole and voila! They were able to clean out the bolt's socket today and finish the job. Shades of Apollo 13 -- when engineers threw parts on a table and brainstormed a solution, which saved the crew.
A noble hack.