Ariel Owners Motorcycle Club

The Altette horn on my ‘54 VH rather surprisingly works quite well, given its condition. It gives out quite a throaty honk, but in this day and age, one tends to feel that its unlikely to disturb the insular equilibrium of SUV drivers passing at 85mph+. Anyway, apart from distinctly shabby or absent paintwork, it is missing several of the fasteners around the bezel, and I sincerely doubt that any of them are original to the horn. I’m struggling to work out what replacements I might need to acquire in order to put things right

As you can see from the first pic, only three out of six are actually present. Two mount the horn to the bracket but appear not to be original, the other one appears to be larger – a 1BA cheesehead screw threaded directly into the body of the horn. This screw will also thread into two of the other vacant holes, but in the third, it passes straight through. Should this horn have the dome/acorn nuts that I see in photos of other bikes of the period? How does that work when there are apparently a variety of different size and thread screws making up the set?

There are reproduction bezels complete with fastenings available, but I don’t really need a new bezel and I’m not confident that the supplied fastenings would work either… the second photo below, cribbed from the interweb, seems to indicate the hotch-potch mixture of different thread sizes etc. Some appear to be studs, some are screws, yet all appear to have the same size chrome dome nut on top?

Any insights greatly appreciated!

That looks quite similar to the one on my '42 W/NG which is an ex-WD horn:
The one on my '51 SQ4 has the same adjuster but uses the acorn nuts:
From what I've learned over the years, the acorn nuts are later and the bezel shape changes, albeit subtly.