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Whenever I get a car w/a sunroof,I clean the tracks with w-d and a toothbrush,then hit it with a nice dose of white lithium grease
Ideally ya wanna take out the headliner.Remove the s/r assembly and douche and grease all the moving parts, clean connections etc.
I just did it in my 93 took half a saturday and, 10 bucks for chemicals.