Grundig T70-540 (CUC5310 chassis) picture roll when using SCART input

Hi,

I have a problem with my Grundig T70-540 (CUC5310 chassis) and I wonder if anyone here could throw some light on it please?

If I use the SCART input, the picture will roll whenever there is something bright in the picture.

Picture is perfectly stable if there are no bright areas.

Picture is perfectly stable if I use the tuner instead of SCART, even with bright picture.

Any help/suggestions would be really appreciated.

Thanks, Chris.