I did! From 2007 to 2015 I was a gas pump calibrater. I worked for a company that did all things gas station. From new construction to simple maintenance. I was licensed by the state of Michigan to cut them off, adjust the meter, verify calibration, and install new seals. My seal had my initials and the company's initials and was registered with the state. My test equipment was calibrated in the state's laboratory and was licensed by the state, thus giving me most of the authority of a government agent, but still being a private contractor. I was hired by the station's owner to calibrate all the meters usually once a year, or if there was ever a problem.