I later read on a forum (I've forgotten which one), that the printed replacement part will break as it could not possibly be as strong as the original one. That did had some truth to it...
My blender did break again. It only survived for long enough to make 11 banana shakes, and I now know, why the original part was made of rubber rather than plastic. The top and bottom part of the blender are not aligned with each other, so the rubber "gear" was acting as a flexible coupler to compensate for the error in design.
My print was made from black ABS, which is, of course, rigid. Thus it was doomed from the start.
The correct solution would be to print the part from flexible plastic. I was lucky to receive some soft pla samples from Kaipa, which has the consistency of chewing gum when printed. It was a perfect candidate for a flexible replacement part, and with my new Arcol.hu Hot-end v3.0 I was finally able to print with it:
(I didn't remove all of the support material, as it has no effect on functionality.)
I assembled it the way I described in my previous post:
I do hope this one will last much longer then the previous version. The blender is not of very good quality, so I would be best of buying a new one, but I expect this repair last another year with my limited usage.