If the leak persists, the first thing to do is to identify the brand and model number of the black and brass kitchen tap. Visit the manufacturer's website or call their customer service. Some brands of faucets even provide replacement cartridges for free. You can also purchase them from the manufacturer. If none of these steps work, you should consider purchasing a leak repair kit. Install the kit by following the instructions and using the parts provided. There are four types of valves, each with its own unique repair procedure.