RMcB

Hi again everyone. The mystery of the non-functioning horn continues. I bought a replacement rotary coupler. I bought the wrong rotary coupler! But re-looking of the photos this evening, the part number of the part that was already fitted to the car (on the right of the photo?doesn't seem to match those available on eBay. I'm confused. What part number do o I actually need? Is it possible that the previous owner was in there before me and fitted the wrong part, meaning that the airbag (appears) to work properly, but the horn doesn't?