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driftson old stuff ususally the goretex membrane has failed (jacket will have flakes like dandruff or if its a lined shell youll hear/feel stuff in the lining) and the seam taping is falling apart, best you can do is nikwax it and make it somewhat water resistant which is good enough if you ski in a dry climate but if its wet leave that jacket at home.
you can go through and re tape the seams but really its not worth the effort on a jacket that old, old goretex just fails eventually.
I wear a 90s TNF mountain light shell sometimes and have nikwaxed it, still wets out eventually.