Hi I had the same problem with the screen on a S/H hood from a scrap yard, zip would not move so I used WD40 sparingly and then worked it back and forth spraying a little here and there. Now works fine, not sure what to suggest about the missing metal end as it would have to be very thin metal to repair that, maybe some plastic and Araldite. Good luck,
Regards D4KGP (Glyn)

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