I have never seen a magnet go bad in a door seal. Most of the time something is in the way or the hinges may need to be adjusted.
I once drove 45 miles one way to push a crisper drawer in about 1/2 inch because it was keeping the refrigerator door from closing.
I even told them on the phone that was probably all that was wrong.
This may not be your case, but it's what I have experienced over the years.
To adjust the door hinges simply loosen up the screws that hold the hinges in place. Then hold the door were you want it to be and tighten the hinge screws back down.