Taking head temperatures on the 36 roadster I have been working on this past week I had a few problems with the readings. The red laser light ALWAYS worked but the display wouldn't always work and sometimes the readings came on after releasing the trigger. Yesterday the red light still worked but no display at all. Pulled the 9 volt battery and it only had 8.5 volts. Put a new battery in and it now has the temperature display working ALL the time. G.M.