An out-of-focus picture is usually caused by poor regulation of the Hi-Voltage circuits. In these older Sonys' it can mean poor solder joints in the horizontal output stages. Check all solder joints on the flyback transformer and filter capacitors on the secondary low voltage side. A less common problem would be a short in the picture tube or arcing in the focus block. Any of these problems will require the services of a competent service technician. This old of a set should not be considered for repair, but replaced with a newer flat screen.