I have zero expierience with the cleaning and adjustment of surveying equipment. I would not try to disassemble or try to adjust any piece of precision measuring equipment unless I am 100% sure that I am capable of precise calibration. Not having any knowledge of what this instrument is being used for (determining property lines, leveling buildings, etc.) I would not give advice that could lead to potential monetary damages. The standard practice in business is to have any measuring equipment frequently calibrated to an NIST tracable device with at least 10x greater resolution than the instrument being calibrated. I am a firm believer in the old saying "If it is not broken, then do not fix it. And if it is broken then fix it only if you know how to, or find somebody who does". Trial and error is one method of learning. I like to refer to this method as the "Hard way". My previous response did not mean "Don't", it meant "Do it right and save yourself some grief".

James Zdunic.