Like we've been saying, the 621 is tricky to get right. Once, when I was able to luck onto just the right focal length and skew, I got just about everything that was possible to get. So the thing will work well if you get it right.
I'm not familiar with using meters. I will say that, for speed and convenience and pretty good accuracy, wireless radio headphones work for me. I set my receiver to beep on scan so the stronger the signal the more rapid and higher pitched the beeps get. I hook the sending unit to audio out, set the receiver to a hot transponder on the satellite you are going for, and then go out and adjust for the best beeps. The wireless headphones are cheap and they leave both hands free to adjust this and that. And, when you hear the beeps, you know that's the signal at the receiver you are using.
A guy on another site a couple of years ago suggested the method. After dragging extension cords, little tvs and receivers up ladders, I was ready to try something else. This wireless headphone thing just works. All I bring up to my dish is one crescent wrench