Well Alessandro I though the very same thing that the motor runs sort of weakly. I went it to a technician the other day and he told me that it was the pin (claw?) which is causing the problem.
As Jeo pointed, I checked the pin which was moving but the guy told me it may be broken or damaged as it was very soft and small comparing of the other cameras he had there. I left him the camera for a couple of day to see if he can do anything . I'm picking up today, I'll try what you both advised and if still not working send it to this German Nizo specialist named Kurt.
Thank you loads for the advice I hope Lolita ( that's her name) will get back to life soon.