I supply picture of a faulty printout. It shows the first layer. Slicing was done with repetier/cura 1.0.6 (recommended by Velleman). Result looks ok in repetier but completely different at printout.
Skirt was missing on side closest to the camera
When filling first layer the machine made a fan-like start (arrow 1 in photo)
Later the first layer was corrupted along the edge shown at arrow 2 in photo.
It seems that on axis is not sliding correctly when reaching the right end of the printer (If the print is oriented like in the printer it must be the X axis).
You’ll have to realign the printer. Check the procedure in the Wiki.
I have found something that might explain parts of the problem - screws in pullies were not tight enough. Actually I replaced most of them with ordinary screws and also used Locktite. Still, friction in the axes does not explain the fan-like printout you can see at the rightmost arrow + lack of skirt at nearest side of the printout… My personal guess is that there is a bug in cura that causes these problems when sliced file is too complicated. Netfabb did not complain (!) I have simplified the original using a clean extension in Sketchup, then it looks better. I’m currently testing…
Finally I found the solution of my problem - the object was too large and printout was limited by the max X-range (200). When that happens, you get no skirt and odd things might appear - like on my photo.