Stepper motors, lumpy bumpy notchy??

[chefsnade]

Is this normal when moving by hand, i feel two notches/bumps/lumps mid way and two at each end. To start of with o thought it might be a defect on the rail where the bearing runs on, but the gap apart makes me think it's mechanical, possible where the poles line up?? Regards
alfawise u30
longer 42BYGH40H-2-19D
KH 2018 12 20