1. Check the condition of the yoke before each use
Check the power cord and switch to make sure they're in good condition. Check that the legs can bend to conform to the inspection surface. Check the feet to make sure they can make even contact with the inspection surface. The more contact area, the better.
2. Use a calibrated test weight to verify yoke strength
An AC yoke must lift 10 lb. / 4.5 kg, and a DC yoke must lift 50 lb. / 22.7 kg. Using just any piece of steel for the dead weight check can create a hazard for the operator; if the weight is not balanced it could slip off the yoke and drop. Calibrated test weights include alignment features to keep the weight balanced on the yoke, allowing you to perform the dead weight check safely.