Start by contacting Origin Live, http://www.originlive.com/, they have an extensive history with the Rega arms. You could also buy one of their arms and sell your existing unit. There are several retailers for Origin products. Or you could rewire the arm yourself, there's not much to it on a Rega arm. I don't have the time to find them right now but the instructions are on the internet.

I had my RB 250 rewired with the Incognito rewire which uses Cardas wire. The wire is continuous from cartridge clips to rca plugs. If you are handy here is a link to purchase just the harness.
http://store.acousticsounds.com/browse_detail.cfm?Title_ID=28758

The rewire is also available in silver and you can find more information at www.hifiaccessoriesclub.com

The rewire is a great improvement.