This is purely a stop gap measure, though I have no intention of replacing mine. I used the same spray glue we use for the hood pad. Poke some small holes liner in appropriate spots for your sag. Use wand with spray can, put wand thru hole and while spraying turn can around 360 to coat inner liner and roof. Let the glue set up and then rub with palm of hand to stick liner to roof. At least this procedure keeps the liner off the heads of back seat passengers.

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1981 240d
Newport,RI