Lack of smoothness / homogeneity in several first layers of print
There are several solution you should check in this order : 

1"

The part is printed too close to bed: measure the first layer with a digital caliper to mach your first layer thikness, usualy 0.35&nbsp;mm like so:



2"

Verify that there is no bevel on the first layer if the part looks like this : U make it look like this  ■ and see if it changes something.



3"

Maybe it is a cooling / temperature problem. the bed should be at max 70&nbsp;&deg;C for PLA and check the cooling of the noozle. 



4"

Check for an over extrusion problem! When you ask for 100&nbsp;mm of filament, does it push 500&nbsp;mm through? If so change this soon.