Don't know if I am going to have to just replace the zip in the end, but obviously would rather open the original zipper. It is a 40s Jacqmar fabric cotton dress with a side zipper that it is completely closed to the very top and stuck solid. Bit tricky to apply anything to the teeth as they are so firmly closed? Dress appears unworn... I don't think anyone has ever managed to get the zip undone!! So good and bad there.. any ideas?