evidence of Dr. Cooper established that there was a high degree of unreliability with respect to the screening device: Dr. Cooper testified initial result of .101 on March 6, '98, showed that an alcohol standard of .100 produced an initial result of .101, and thus the person calibrating the screening device would break the seal and turn a screw so that the final result would be .100. He testified that a screening device should only fluctuate on the initial reading from .09 to .11. He testified that the initial result of .084 on March 23, '98, should have raised immediate suspicion that the screening device required further maintenance and not a calibration check. He further testified that the .084 result cast a serious shadow on the reliability of the machine