Do the following if you have overextrusion

1. Check the Filament Diameter

Ensure the filament diameter entered in the slicing program is the same diameter as what you are using.

2. Calibrate E-Steps

If the extruder has not been calibrated, the printer may be moving more filament through the extruder than it thinks it is. A helpful guide on how to calibrate e-steps can be found here.

3. Decrease the Flow

Try progressively decreasing the material flow rate in increments of 2.5% until better results are achieved.

4. Decrease the Print Temperature

If the temperature is too high for the material you are using, extra material will ooze through from the nozzle. Try progressively decreasing the print temperature in increments of 5 degrees until better results are achieved.