I thought I should mention the vibration and the leveling feet of the IBT first, even though that is unlikely the problem. If it is the problem, then that easily fixed. If that is not the cause of the instability, then the cause might be with the angle measurement system. The angle measurement is done by applying +12VDC and -12VDC (approximately) across the Pendulum Potentiometer (Pot). When the Pendulum moves, the “wiper” on the Pendulum Pot moves and voltage at the wiper changes (Pendulum Pot output) indicating the Pendulum’s new position. The Pendulum Pot’s wiper voltage (output) is then saved in a “peak detector” circuit and that saved peak voltage is measured by the AV-3 microcomputer.