Questions about Faber-Castell E-motion

I bought this fountain pen with an M nib. The stroke width depends somewhat on the ink (it works best with Faber-Castell cartridges), but it is closer to 0.7 than 0.5mm. The B nib should therefore be wider than 0.7. By the way, the fountain pen has worked smoothly and reliably so far, I can only recommend it.

This is a size M.

Unfortunately we do not understand your question, is it possible to formulate it differently? Thank you very much in advance :)

Unfortunately, I could not find a suitable replacement spring in our range.

We can do that! :) Now available at the following link: Faber-Castell e-motion fountain pen pure black F (Black)

It only says "medium pen".

No, unfortunately that is not possible.