A door gasket rarely fails all at once. It loses contact in one corner, then along one edge, and the appliance works harder to hold its temperature until something else gives. The early signs are small, and a repeated check catches them before the cabinet or the floor takes damage.
Watch for the early signs
Look for a gap at a corner or along the bottom edge when the door is closed. Feel for a cold draft at the seam with your hand. Check for frost or water beads on the bottom edge of the door opening, and for condensation on the outside of the cabinet near the seam. Notice whether the unit runs longer than it used to before it shuts off.
Run a paper test
Close the door on a sheet of paper so that it sits halfway out of the seam. Pull gently. Move the paper around the whole perimeter, testing at the top, both sides, and the bottom. Where the paper slides out with no resistance, the seal has lost its grip at that spot. Repeat the test at the same points each time so the results compare.
Keep a written record
Write down each check in a notebook kept with the appliance manual. Record the location of any weak spot, what you saw, and any change from the last check. A written record shows whether a weak spot is growing, and it gives a repair person something concrete to examine.
Check the paperwork for wear items
Gaskets are often treated as wear items. Before you rely on any service contract for this part, read whether the paperwork excludes wear parts, seals, or parts that deteriorate over time. The exclusion wording decides the question, and a general promise of repair does not answer it.
This method does not diagnose the appliance, and it does not replace a qualified repair person. Ask that person to inspect any weak spot you record, and keep the notebook for that visit.