To fix carpet buckling, you’ll need a knee kicker, power stretcher, or carpet stretcher tool. Start by removing all furniture from the affected area. Use the knee kicker to tighten the carpet by hooking it under the seam and pulling it towards you. For larger areas, use a power stretcher or carpet stretcher tool to stretch the carpet more evenly. Secure the carpet by inserting tack strips around the perimeter of the room and hammering them into the subfloor. Finally, reattach the furniture and vacuum the carpet to restore its appearance.