[agering]

If inaccuracy appears in operation that you need to do on drive installing the driftage of the zero by resistor R2 (OFFSET). If it is parameter N007 #7(ADFT)=1, that necessary parameters N124-N127 to set in 0.
Change OFFSET possible to see using diagnosticses X=N800, Y=N801, Z=N802, e.t.c.
After setting the value greatly drawn near to 0, possible adjust the gain by resistor R1(GAIN). This will give acerbity of the positioning.

[SadieD]

If inaccuracy appears in operation that you need to do on drive installing the driftage of the zero by resistor R2 (OFFSET). If it is parameter N007 #7(ADFT)=1, that necessary parameters N124-N127 to set in 0.
Change OFFSET possible to see using diagnosticses X=N800, Y=N801, Z=N802, e.t.c.
After setting the value greatly drawn near to 0, possible adjust the gain by resistor R1(GAIN). This will give acerbity of the positioning.

I'm going to give this a try. The procedure is also mentioned here by tc429:
http://www.cnc-arena.com/en/forum/circular-interpolation-fanuc-6m-not-round--222446.html