How can I fix a pull cord switch for light/extractor fan?

The pull cord switch in the bathroom is a bit hit and miss lately. It controls the light and extractor fan all in one. I've bought a new pull cord switch but was a bit thrown when I looked at the existing one's wiring. Two reds connected to separate terminals in the old fitting; two earths together on the earth screw; two blacks in separate terminals in a separate terminal block. Do I just follow a similar pattern?