EKCO CT102: Green stripes on picture

There are five broad, vertical green stripes across the picture, evenly spaced. The fault is most noticeable on grey-blue backgrounds, but affects all colours.

Solution

Check the BC147 or BC107 transistor in position VT28, this is the flyback suppression transistor in the cathode lead of the PL803 luminance output valve on the colour difference amplifier panel. Also suspect  a faulty line linearity choke L39 which can be shorted as a quick check.