If you have a manual gearbox, the cruise control lines will be redundant on the rotary assembly, so you can check the continuity on those, which of good, you can swap the horn wiring over to use instead.
The problem with these rotary assemblies is that the copper tracks fracture over time on the flexible surface, which is why it only end up working in certain wheel positions.
I ended up buying a new replacement from Bearmach, when mine completely died.