Finally I put my Constructor I building log online. Check it here.
It seems like this model is currently discontinued, which is sad, despite all the issues (I completely ignored some component quality issues in my post, I think they’re common across Makeblock products.).
I think it should be better to make improved version of Constructor kit rather than making preassembled 3d printer like mElephant.
But anyway, may be my experience of some interest for people trying 3D printing.