Vertical blinds are made from a rigid plastic material, metal or fabric. The problem with these blinds is eventually they will start to break down from wear and tear of turning them open and closed. Since blinds are not cheap to replace, you can instead fix the clip hole on the top of the slat with a few easy steps.
Unhook the broken blind carefully. Flip the blind upside down for a clean slate to make the new clip hole.
Fold your blind slat in half gently until the edges are lined up. Use your marker to draw a dot where the broken clip hole lines up.
Slip the edge of the blind into your three-hole puncher. Center up the dot and punch your new hole.
Bring the new clip hole up and slide it into the slat holder. You can repeat these steps as needed for other clip holes that break on other blinds.