Looking at the percent load gauge for example, there is a little slot, bottom center below the glass. A really small flathead can go in it to "adjust" the gauge. From the factory, they are usually perfectly up & down. They can be adjusted as needed as they will read off for many reasons, one being time & being slammed around for years. So with a known good meter, you can adjust the gauge to what is proper. Just keep in mind, if moisture gets / has gotten in there, this adjustment can fail & make a one time adjustment & fail.... leaving you with a gauge VERY off. But, I have found when this happens, the gauge is on it's last leg anyways. Also, the adjustment isn't a big range. It's just to tweak it a little. Hope this all makes sense!
