You could perform a quick test before thinking about mastering the robot. Jog the robot in a straight line in X or Y direction relative to world or to a user frame which is already taught (if there is one). If the TCP deviates from the straight X or Y path then mastering could help. Check the position of the TCP also visual and not only by the position data.
Recalibrating the burner does not help. Moving in the X and Y plane works fine. The inaccuracy is noticeable only when passing circular seams and turning the burner. Here is the video I recorded:https://youtu.be/A24RWnW0rwI