Hi!
This is made of a sheet of some kind of plastic. Four rivets going through teflon washers old it in place. Also the teflon washers are positioned in such a way that the swivel won't spin around the foil.
I'm thinking of ordering this:
http://www.ebay.co.uk/itm/6495-PTFE-...item4ac49791f5
For 9 euro I'll try to fabricate a replacement part.
Cheers,
Luis