I assume there is supposed to be a ground wire in the steering wheel column and power for the horn. Mine does not have the ground wire. I suspect it was a hastily reassembled job. I have a temp solution but what is the way they used to be from the factory? How much disassembly and fishing do I have to do to get it in there? I have a Momo steering wheel, not stock.

The Momo wheel complicates things, early factory has a plunger that grounds the horn making a circuit, later version has a grounding ring that connects to the batwing with a small connector.
My first 914 had an aftermarket steering wheel the horn was activated by a button on the dash. Not my solution.

On my Momo installations I have a ground wire with a spade at the back of the button and about a 2" section of stripped wire at the other end sandwiched between the adapter base and the washer below the nut holding the adapter on. The other wire comes from the stock contact ring that touches the finger on the turn signal switch assembly. If you're missing the contact ring it likely won't work at all.

You need this ground ring for the Momo steering wheel:

https://ltbautosports.com/momo-horn-button-retaining-ring/

It is captured in between the Mom wheel and adapter. The hot wire from the horn goes to one terminal on the horn button, and a wire goes from the other terminal on the horn button to this ground ring.

Otherwise you can ground the wire to some other place within the adapter.

Click to view attachment

That explains some things, thanks.

This should do the trick, thanks for the tip.

This is similar to what the PO had done.

I got this ring that fits behind my Momo Prototipo. However this doesn't seem to work on the Momo die cast type metal adapter that fits perfectly onto my 914 steering shaft splines.

Is there any way how I can make it work????

I got this ring that fits behind my Momo Prototipo. However this doesn't seem to work on the Momo die cast type metal adapter that fits perfectly onto my 914 steering shaft splines.

Is there any way how I can make it work????
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Exactly my situation too - cast momo hub except that I also have the JWest eccentric adapter. The tang on the momo grounding ring promptly snapped off. I did as sportlicherFahrer described and ran a small wire from the ground on the back of the momo horn and sandwiched the stripped end between the hub and the adapter. You just need to ground the wire somewhere onto the hub.