Hey everyone, I have an original Prusa i3 mk2, I have had it since June 27, 2016. It has been printing perfectly until now. Now I have weird layers showing on my models. They only happen on 200-300 microns, but 100 microns is perfect. Also, it happens with both PLA, and Abs. I have tried using curs rather than s3d, and it still happens. I am pretty sure it is not under extrusion, as I have upped my extrusion multiplier up a lot, and the same thing happens. I have attached pictures of Only an Abs print, as that is the only one I have printed currently. It is the same for PLA. Please get back to me shortly.
I had some similar lines with bad filament. The roll of Prusa filament that came with my printer works perfectly, but I ordered some $18 filament from walmart, and it prints great at 100 microns like you said and poorly at 300.