An exercise device for assisting stretching exercises, which includes a stretch support frame and a vibrator. When the fuel in the surge chamber falls below a defined minimum, the supply of power to a delivery pump that is driven by an electromotor is interrupted, thereby preventing the delivery pump from delivering air when the surge chamber is empty. Empirical and theoretical cumulative distribution functions for the time intervals are calculated, and compared to identify a malfunctioning terminal not operating in accordance with the protocol.