Horn not working. How is steering column earthed ?

[MagicWagon]

The horn on my 1981 Aircooled Autosleeper has stopped working.
I ruled out fuse and horn itself because I took the steering wheel off and connected a wire from the copper connector under the steering wheel (that rubs on the ring on the wheel) to the battery earth and the horn sounds.
However, if I connect that same wire to the threaded centre of the steering column it does not.
There is no continuity between the chassis and the centre of the steering column (as there is on my other van) so I assume this is the problem.
How should the column be earthed ?
Thanks.

[bigherb]

There is a link wire across the rubber steering coupling at the bottom of the column it usually corrodes.
It is actually under the coupling I just fit them above as it is easier.



It then runs up the centre of the lower column and connects to the upper column via a Lucar connector.

[MagicWagon]

Brilliant, thanks for those pics. Finally got it working after 5 hours trying.
When a mechanic replaced the bush shown in the picture they must not have replaced the wires joining the bolts.
Also, strangely, there is a wire connecting the upper and lower steering column sections.
The wire comes out of the inside of the lower section, and should attach to a spade tab on the upper section. Mine was attached to a spade tab on the lower section (found by comparing to my other van).
I don't understand why a tab is needed on the lower section though.
Anyway. All working now.
Thanks.