Why is a new or recently overhauled air-driven gyro from Mid-Continent Instruments slow to erect, not indicating roll or pitch level and/or tumbling?
After verifying that the unit is connected properly (air inlet and outlet ports) and that there is adequate vacuum/pressure be aware that air driven instruments frequently fail due to contamination in the air system (including the lines, filter and pump). Check the air inlet port on the gyro to be sure that there is no sign of contamination visible on the internal mesh screen. Caution: very small particles may pass through these screens and will damage the bearings in the instrument.