This is a prototype Angle Solver MK 13 Mod 0 Serial number 2 created for the US Navy by Librascope. Most of the dials move when actuated but some are sticky. I’ve never thought of trying to open it up to clean. The plate on the upper left hand corner clearly shows a torpedo boat set up with two torpedo’s on each side. I’ve had this unit for almost 20 years and it’s time to find a new home for this one of a kind item.