Two non-symetrical ball bearings removed from the Acme Thread shaft. Bearings were found installed with the words (bearing number) facing towards the magnet. This is the right orientation. The downstream bearing was found to have been siezed. Best guess is that someone drove into the wooden block with the cryostat. This would have put too much strain on the bearing in the wrong direction. Two bearings ordered. 7200B (part #7200BEP from Motion Industries Canada LTD.). Screw to be cleaned, greased and reinstalled with the new bearings when they arrive.