I recently purchased a set of these from Ebay.
The guy charged the earth, supplied duff bulbs then wanted to charge £15 each to replace them.
You can buy them from
www.far.it You do need to drill the faring and head frame (the bit that holds the top faring on).
Chuck the standard 5W amber bulb away – as it is about as much use as a chocolate teapot..
I’ve found a place on Ebay that sells 21W clear bulbs (10x2mm base wedge) – great if you want amber lenses.
If you want or have clear lenses I can supply these same bulbs, but painted with amber paint for £4.99 each, that’s £ 3 cheaper than anyone else.