I recently purchased a late 80s/ early 90s Burley Duet. I love the bike but I need to replace the brake cables. The left brake lever operates the drum brake and the right lever operates both the front and back rim brakes. I am not sure how to go about replacing the cables on the right lever. It look like both cables go into the lever but I am not sure if they are a special design or if I can use regular cables. Has anyone replaced these and what advice can you give me?