Troubleshooting Problem Solution Difficulty in calibrating C-Level Test that the C-Level is functioning correctly by pressing and releasing the calibrate button with nothing but air behind the device. If it flashes and beeps twice, it is functioning correctly. If the C-Level flashes but does not beep when the calibrate button is pressed, re-install the battery making certain that nothing is touching the yellow label on the back of the unit and test calibration again. Difficulty in determining the level of some drums There are some non-metallic drums that are more that 3/8” thick. These drums can cause irregular results. Try using on a different location of the drum. There are some drums that have erratic wall thicknesses. Try using on a different location of the drum. The lights on the C-Level are not as bright as they were when the unit was new The battery may be getting weak. Try replacing the battery per the instructions.