The Mark2 part files from Github was not working perfectly for me, so I made some changes.

1. In the BOM, all magnets are 6x3mm. But the dimensions in the head are designed for 6x4 magnets, which results in no gap between the head and the coupling. I made the holes on head-a 1mm shallower so it works with 6x3 magnets.
2. the holes for magnets were 6.2mm in the original model, which is too loose for my print. I changed all to 6.04mm for a tight fit.
3. I cut away some gaps around the magnets so they can be easily removed with a screw driver without totally tearing apart the model.