thanks Neal, but no; i wouldn't install the mmu when the printer doesnt work well yet.
we ested it and it seemed that the fan was broken. We got quite decent prints without fan, wich made us believe that it would be much better with fan, and started installing MMU.
now, we have had 10-15 hours in it, and it had printed a nice omnom and candy with multi material.
however, we can not reproduce this anymore.
All prints after go wrong on the first layer(s) due not sticking.
With the z-calibration most is doing great. When printing starts, its crap.
Also what we fount, is that the Z-calibration is done, the actual print is starting at a different (higher) height again.
so, what it looks like,is that the z-calibration isnt stored, and the prints are not adapted to the new calibrated z value.
what also is quite annoing, is that all kindsof settings like temp. and bed temp seem to reset when the file-to-be-printed is starting. So, every file seems to have the need to be edited in 3dslicer again for the new wanted temps and put on sd, and loaded again, wich is odd...
i hope im a noob and im missing something...