Sorry but I realised I was also looking at the MS6000 with Beo4 manual.
There are some other TVs (eg LS4500) that use SHIFT 9 to activate S Video, but there is no further instruction regarding how to get the sound through SCART.
Can I just check: Are you selecting the input using V.TAPE, and then pressing SHIFT 9 to try to bring in the S- Video input? Can I also just check that you are pressing SHIFT then 9, and not the buttons together?