I don’t have a MPCNC yet (busy printing) but know something about 3D-printing.
First I think the filament is not sticking well enough on the surface. You have to make sure the printbed surface is suitable. If you use PLA, take a smooth surface and use blue painters tape on it. Or use a glassplate with special 3D printing glue (aerosol).
Second I think the X and Y-axis are not well calibrated. Maybe to much backlash to get the filament strokes exactly side by side.
I don’t know what your setting are (and nozzle diam.) but I think you have to experiment with the settings in Repetier:
– It looks like the flowrate is too high. In Repetier: Configuration > Filament tab > flow. Or while printing in the Manual Control tab.
– Try an infill overlap of 5%
– Try Retraction speed of 140 mm/s and retraction distance 4 mm.
– PLA temperature about 190 degrees.
But, as I said, I don’t use a MPCNC printer and different printers has different settings, but you can easily play with the settings and look for the result…