We had a question recently about decreasing friction in a zip, but this is the opposite case: I have a couple of zips that slide down by themselves. Is there anything I can apply to add a bit of friction/stiffness to the mechanism?
One of them is on a bike jersey where the zip used to be a locking type but is damaged (I'm considering replacing the zip if I can't find a solution); the other has always slipped since it was new.
