As the 'Improving' thread is getting a little long and other people seem to be making better progress...
What is causing these errors?
The top and bottom perimeters measure very close to the 30mm I've set. The infill is set to 10% but appears to be over extruding which would explain the step in the print and I can hear the nozzle dragging when it's printing.
The corner overhand and burn though??