Carefully thread the metering tip into the tip holder using the metering tip driver tool. DO NOT OVERTIGHTEN!
If the tip head breaks off due to overtightening, try removing it with a small eyeglass screwdriver. Take care to avoid damaging (scratching) the inside threads of the tip holder, or the tip holder may need to be replaced.
The procedure is the same for a wall-mounted unit with a check valve that is threaded for metering tips.