What is "seger"? online translation from italian/etc doesn't come up with anything to english. (swedish says it is "victory", pretty sure that's not what you mean).
I don't know of a specific guide to putting one of those motors back together once disassembled; it's manual (if available) from bafang is unlikely to include any information about it's insides.
If you post good clear pictures of all the parts you have, we can suggest likely reassembly orders.