Audio tech stylus replacement source - any help?

I have a vintage Audio Technical moving coil cartridge. I'm advised the stylus in worn and needs replacing.
No outward identification of model, but the color is gold (top) above black.
I'm told this model is well passed available, perhaps 20 or more years, but well worth saving - one
of the very best of it's time, I'm told.
Can anyone identify from this feeble description what this model might be?  Also, Is there a source that can effect a stylus replacement on such an older model A/T?
Any help is much appreciated, fellow addicts!Bo