Steps / mm are off - but why?

Hi,

I just swapped the xy and e-motors of my Prusa MK3. The new motors on paper have the same Specs as the LDOs, esp the 1.8 degrees per step.

To my surprise I had to adjust the steps per mm by roughly 5% (X is 104 istead of 100)

Now I am wondering how this could be, because no parameter has changed on the mechanical side - could this be an electrical problem? Or is this within the tolerances of motors?