If your line of site is clear and you are not getting all your visible sats, then your arc must be a smidgen off.
I use to get 10GR until the leaves filled in the tree. Check your line of site first. Double check all your angle calculations with setting the angle of the motor and angle of the attached dish. Is your south satellite your true south satellite? What I did to set my azimuth was to confirm all my dish and motor angles. Set my 0 on the motor. Tuned into a strong signal like
IA5 using USALS which moved my dish to IA5 (what it thought was IA5). I then rotated the whole assembly of the dish and motor on its pole until I got my strong signal. With the horizontal pin pointed, I then loosened the dish and adjusted its angle up and down until I got the strongest signal possible. That set me up well. I was able to get 40 to 123.... a lot of trees limited other longitudes.
I used Google Earth to get my exact latitude and longitude.
It is a pain, but once you find your sats 4 or 5 times, it becomes easier. I lost signal a couple of times when snow or wind repositioned my dish. LOL