What cleaner should be used to clean the inside of vaccum gyro horizons and altimeter
My friend has just boughts Cessna 150 and found out that the vaccum gyro horizon is not working properly. He opened it up and found out that inside of the instrument is covered up with a white powder. Looks like its a corrosion but I am not sure. If this is a corrosion why is it white? What cleaner sholud be used to get rid of this white stuff so that not damage the instrument?
Many thanks