I 've been having trouble finding a gasket leak in my SamSung French door refrigerator.
The normal methods of pulling a piece of paper through the gasket and door did not detect the problem.
So I developed a different way to detect leaks ore accurately and precisely:
Obtain apice of 1/4 inch flexible tubing,about 3 feet long,and a small piece of silicon medical tubing,1/4 inch ID.
Attach the tubing to the drain tube under the refrigerator,using the medical tubing as a coupling between them.
Now blow into the tubing and check for leaks around the gasket using kid's bubble blowing liquid.
Any leaks will become easily detectable.
See this link for making leak detector.
https://www.thoughtco.com/bubbles-that-dont-pop-recipe-603922