Today i decided to try something different. Had this block of solid rust that once was a nice micrometer, but which had been exposed to salt air and which was a solid block when I got it. So decided, as I had nothing to lose, to try to free it and derust it. Started by first giving a 2 hour soak in paint thinners, which got all the oil and most of the black paint off, so perfect for the next stage. Stripped it apart as far as possible, so I could do the pieces all at once.
Then it went for a swim in vinegar, and after a half hour nothing, so I decided to try electrolysis to shift the rust. Needed an anode, so used a left over carbon vacuum pump vane, as they are a service item, and i had some spares. then simply connected a 12V battery to the anode, and the micrometer as the cathode.
Bubbles, and after an hour there was a difference, so cleaned and back in again. Then again a swim and a clean, and after 2 hours finally I could see the metal on the shaft, and after some gentle persuasion with pliers it started to move in the housing.
Cleaned, washed, dunked in the thinners again then drowned in some spray oil and put the kit together, and then reset the alignment ( still not right, 3 micrometers out but fixable) and ran it a few times then oiled it again till tomorrow.