Sturmey Archer were one of the most common gearboxes in the vintage era. They were fitted to many makes. They made a whole range of gearboxes, two speed, three speed, Featherweight, Lightweight, Heavyweight. That said you won't get far without specifying what particular model of Sturmey Archer is fitted to your Raleigh.
I suggest you start off by identifying what box you have and then buying a spare parts list so you know exactly what you're after. The VMCC Library will be able to help.
Cheers,