I did use 83W and it is at 0 position on the motor.
Richo,
Currently, the satellite at 81.0°W is the moved Intelsat 3R and it is inclined 1.6°. Although it is very handy to utilize your truest southern satellite, it is not entirely required.
The problem here is in how you aligned to it. If 81.0°W is your truest southern satellite, you cannot dial your motor in to the zero degree mark and then align for 83.0°W. You need to drive the motor 2° west of zero and then align for 83.0°W.
This is most easy to accomplish using USALS with a H-H motor. Since I don't know anything about your system, this is the only and best way that I can present it to you. In this case (USALS with a H-H motor) you tell the receiver's USALS mode what your latitude and longitude coordinates are and then you command the motor to drive to 83.0°W (which moves it two degrees west of the zero position) and then you align your dish elevation and azimuth for reception from 83.0°W.
What you did was align your dish the best you could starting 2° off from the proper reference. This is why when you move further out on the arc, it seems to overshoot or undershoot the statellites (depending upon which direction your motor is covering the arc).
RADAR