I share the solution for those who have a similar problem: You have to press the head cover and turn clockwise, calculate 1/16 of a turn, then with something thin to lift this cover, a central screw that we must remove will be exposed. Then there are arranged every 120 degrees three legs of about three cm long with some nails out, to remove that component we must put between each leg and the round body, something thinner than a saw blade, with this we get the legs to flex a little inwards and we lift that lid, once removed we have access to the screws and there is no more problem to disassemble it. Thank you.