The back wall of the nut slot may be too shallow. I simply drilled out the bolt hole slightly since I did not have a tool to enlarge the back of the slot. It may make the hole slightly lsrge but the overall performance is still fine.
Glad you found a good solution Daniel. Yes the nut traps can sometimes be tricky since oversizing them can also cause problems so we err towards undersizing
The reason is isn't compatible is that the linear rails in the MK1 are on the outside instead of the inside like on the MK2, so there's no room to mount and fit the mechanism without a full redesign