Having top-quality levels and lasers in your toolbox is a great asset and one that can save a significant amount of time when completing a layout. But like the check engine light on your vehicle, these tools may need a checkup from time to time and possibly a tune-up.
The first question asks, is your level providing level and plumb lines? To verify the level’s accuracy, place the level on a flat horizontal surface like a countertop. Draw a pencil line on the long side and at one end and read the location of the bubble. Without flipping the level over, rotate it 180 degrees (end for end) and place it on the same pencil lines. The bubble should be in the same location as previously viewed. If it is, you are good to go. If the bubble is on the opposite side of the line, you should take a screwdriver and hammer to destroy the bubble tube. This may seem extreme, but do you want to chance using a level that is not accurate on your next job?