The V-Groove Interior Overcut controls where the Blade Retracts from the Fallout (not the Matboard) on the Interior cuts of the Inside Cut of the V-Groove.
The Interior Cut is where the Blade Plunges or Retracts from the Fallout (not the Matboard).
If the Interior Overcut on the Inside Cut of the V-Groove is cut Too Long, Decrease the Interior Overcut on V-Grooves.
If the Interior Overcut on the Inside Cut of the V-Groove is cut Too Short, Increase the Interior Overcut on V-Grooves.