Reading about motor calibration shows that you need to position a drive gear with a tooth at exactly 12 o’clock. I have designed a quick 3D Print to aid this alignment. Basically a plumbob to slip onto the gear.
Print the part, drill a small hole at the top, insert a pin and hang a weighted thread to align with vertical datum.
The datum is 50mm high so 1mm error at the bottom is about 1 degree.
I have not tried this yet as I am waiting for the kit but if someone want’s to try it I can send you the STL.