Thanks a lot for the quick answers guys.
Unfortunately, its going from bad to worse. So far, I've removed that tape and I scraped the inside of the Bowden cable with a razor, to reduce chafing. This did not help, it's seems to be popping off even more often.
As for temp, speed and layer height: I've been printing with PLA, 100mm/sec max or slower, .1mm layer and around 210-220C.
And I've tried to print the diverse solutions you proposed, but the cable always comes off during the print. I even tried to hold it manually, but I don't want to force anything. Anyway, it came off again.
I did manage however to print the Ultimaker extruder clip (http://www.thingiverse.com/thing:46157), but it broke when I tried to put it on. :-| Now that I've changed to ABS, the Bowden cable comes off again.
I'll go to our FabLab tomorrow and print a few of the parts in ABS there. I'll keep you posted.
If you got any other ideas, I'll take them... :mrgreen:
Thanks for the help anyway.
Mich