IRobertI
Thanks for your help!
I'm afraid that the backside of my object is not flat at all, so I cannot turn it around. What amazes me is that before I had my own Ultimaker2 this object was printed via 3DHUBS on an Ultimaker original, and did not show the problems I have.
It looks like the distance between the "lines" of PLA on top of the support material are too far apart or too thin, causing a very irregular surface.
Next, they are fixed too strong to the support material, so it is extremely difficult to separate..
I am new to Ultimaker and these are my first 3D prints, so I do not yet know all terminology... Hope I am clear enough!
Hans