At 10r it is always 5 degrees west at G27 it is 7 degrees west. At 61.5 it is 5 degrees east. Yes everhing is secure. I did adjust the backlash to make it a little tighter. I did use a metric allen wrench and tighten the motor tube. I only use USALS.
More west on the west, and more east on the east. Sounds like the Motor Latitude setting has slipped somehow ( or something happened to the pole being plumb ) . I think I'd take my motor latitude setting about 2 degrees up/down and see what happens. Perhaps you'll see a pattern and a solution.
Mine used to do that a bit before it finally gave out and I had to get another one. If it's consistent, you might possible be able to let it be. I get wind that shifts my dish on occasion and when that happens I usually just have to change the usals setting a degree or two further east or west.... but uh, typically it's a consistent 2 degrees west on all birds or something like that, not one degree on this one, two on that one, five on another. Make sure the pole is absolutely plumb...
It's interesting because it runs right past the satellite and you get a burst of video and audio when you tune 10r. you go out to the motor and there it reads 5 degrees west of where it should be. If you back the motor up USALS drives it back again.
In the year and a half I've been messing about with motors, I have come to a realization that they are NOT an exact science. The receiver you use matters, the dish matters, the motor matters, how you install the pole matters. If any one of those is awry, you will have a problem. if TWO or more is a problem, you might have fellas from four states calling you on your cellphone helping you try to figure out the problem. And one crazy Green guy with his slide rule and abacus trying to explain geometry in an email and deducing motor angles from digital pictures you take.
Worst I ever had personally was a Sonicview 4000 that would make a SG2100 go batty, most of the time all the way west. It would NEVER stop in the same place twice no matter what I did.
I noticed something similar when I was installing my DG380 recently. I had to clear the onboard satellite table in the motor (several times!), then things cleared up. My problem was probably that the motor's reference point was no longer at 0°. This can happen especially when you switch receivers.
I don't know if you have the same problem though. Good luck!