I need to replace the refrigerator and possibly the freezer door gaskets on my Subzero model 550. The refr door does not hold as tightly as it used to; it used to require a major tug, but after 20 years has gotten loose. I have the part numbers from Subzero and they seemed to think that this was too big a job for a regular homeowner and said something about putting glue on the door. Do you have instructions and how big a deal is it? I handy, but not a pro.