[ROVERNET - UK] carburetor service kits/needles

[peter king]

Hi Roverists,

I'm about to order a service kit for my HS6 carbs, and I'm wondering  
what you all advise re: needles. How do I know I need a new needle,  
or should I assume I do regardless of condition? Also, Wadham's lists  
only one needle for the HS6, but other suppliers (like http:// 
www.aptfast.com/APT_Parts/SU_Parts/a_SU_components.htm  ) list many.  
Is there a standard replacement?

Many thanks in advance for any thoughts on this.

Peter