[Jacques Reed]

Thanks all for your inputs:

Yes, I too felt repair might alter the tone especially if heat was involved or some material was attached.

My biggest concern was water getting through it into the electrics but unless I got caught in torrential rain the chances would be negligible.

I might just put it back together and live with it. I guess if you drove like a Mexican taxi driver, always on the horn, the diaphragm might fail quickly from fatigue starting at the holes. Sensible use of it should see it last a long time.

Here's a handy hint for getting the nuts off the screws that hold the horn front to the coil plate:

Those screws will turn when loosening the nuts as there is nothing to prevent it. After a good wire brush of the nuts and exposed threads, and lots of penetrating oil I clamped each screw in the vice from the head to the threaded end to prevent turning and then backed off the nuts until they contacted the vice jaw protectors. I used plastic vice jaw protectors for a bit of grip and prevent damaging the ends of the threads. After that the last few turns were easily done. Also keep adding penetrating oil and work the nuts back and forth a few times before removing from the vice and it will ensure the last few turns of the nut are easy. Strange design for a screw but I guess the designers never though someone would be taking it apart 75 years later.

Attached photo of horn before disassembly. Surprisingly, despite the rust, there was no holes in the rear cover of the horn after it was cleaned up.

Cheers,