Thank you very much Eugenio for your patience and your kindness.
It should be this little piece you show me in the video.
What is its function ? Even if this piece is not in its good place, it doesn't seem to prevent the use of the transport.
The motor tries to move the piece, tries several time, then it stops for security.
I think that this piece has gone up during the transportation, just a little but enough to be out of reach for the gear under.
What do you think about my theory
Thanks again