If the USALS position is calculated 2 degrees out of actual position, the motor and/or dish is not correctly centered on the arc.
Does the dish bracket have a bolt that passes through the motor post or is it a u-bolt type mount? If a u-bolt mount, make sure that the dish is parallel to the motor when the motor is positioned at "0" centered. This can be done by measuring from a point on the dish edge to the center of the motor tube then an identical measurement point on the opposite side of the reflector to the center of the motor tube. Both measurements must be equal to indicate the dish is centered on the motor.
Cheating by offsetting the longitude setting 2 degrees from the correct setting in USALS set-up menu is a work around that will get you by until the motor position can be fixed.
The offset of the longitude setting will not correct the incorrect mechanical setting of the motor and/or dish bracket. Satellites may be tracked near the top (center) of the arc, but will not be track further out near the East/West edges.