Hi Victor,
Thanks a lot for your help.
As I said in my post, I do have balanced everything, but it wasn't enought.
I have changed the motor by a NEMA 17 0.9ยบ in AR axis (I have no problem with DEC), with much more torke. I have solved the problem with skipping steps.
As I am new with EQMOM, I am testing everything, mainly autoguiding. At the end I whant to be able to take good pictures.
Thanks again Victor
Regards
Mateo