Your model U4107....
Was made anywhere between 1977 and 1980 approximately. There were two slight variations with one difference. One had a metal base, and the other is a plastic base. This model was made when Hoover was making that change to the Convertible causing the outer machine to look exactly the same, and bare the same model number, but one be plastic and one metal.
If your Model U4107 has a metal base (not the hood, but the complete chassis that the wheels, and brush roll, and motor screw in to), then your particular machine was made in 1977 or 1978. If yours is plastic, then your machine was made in 1979 or possibly 1980.
