Small layer-shift like features in parts

[PeterWhite76 1]

Hope you guys can help.

 

We've had our S5 for about eleven months and when I'm printing parts with holes or features in, I'm often getting an artifact similar to a layer-shift just in the layers with the hole or features in; once the holes are printed it returns to its original routing.. I've been in contact with my reseller's help desk and after their advice I've checked the short belt tensions, checked the squareness of the pulleys as best I can and the x/y rails are freshly oiled. I was using a custom profile too, but the only things I've ever changed from the recommended settings are wall thickness, top/bottom layers and infill patterns. (The reseller suggested that the recommended settings may remove the issue. I'm still in conversation with the reseller on the subject in the mean time).  I've never fiddled with print speeds so I've always kept them as per the profile. Not everything I print comes out with these artifacts though, it mainly seems to occur in the front third of the print surface. smaller parts right in the middle seem to be unaffected. I rarely print much that goes to the back of the bed.

 

The part I have in the pictures is one that I threw together in fusion 360 to attempt to show up the issue.  I'm using Ultimaker Tough PLA and the "fast" setting in recommended settings.

 

Has anyone come across similar issues and how did you solve it when you did?