mkIII right hand switch component wanted

Hi, on the right hand switch there is an 'off-on'off' lever, picture enclosed. Whilst the switch just about works, you can see the lever is missing the top part that causes the 'notch' effect, when you move the switch from one position to another.

I've tried the normal UK suppliers and these have been out of stock for 15 years, does anyone know if someone has one tucked away somewhere?

Thanks

Greg