The nylon excenter broke and I came up with the model attached. 

Printing: The cam is intended to be printed horizontally, the two other parts are intended to be printed vertically. The ring slides over the cam to avoid the splitting due to the press fit on the motor axle (diameter 3.15mm, with knurling up to 3.3mm). The model has a nominal motor axle diameter of 3mm, this might need to be increased.  The provided 3mf file has both the orientations as well as the slicer (bambu) parameters I chose.  (7 wall loops, 0.08mm layer height, printed in PLA)

Assembly: Slide the ring over the cam. Insert the first bearing, then assemble the seating of the second bearing (with some superglue) and add the second bearing. This should then be slit on the motor axle.  (Note: Fasten the motor with the screws before you slide the excenter on the motor shaft!!!)
I do not know how long that repair will last. Replacing Nylon with PLA is risky, but you can choose other materials. 

Remix: you can remix or tweak the design here in onshape. Any feedback is appreciated. 

Edit 11.06.2024: PLA is not the right material as the motor (and hence the Axle) heats up significantly during use. I will try again either with PETG or ABS. Please share your experiences in the comments.