Worth trying Highbridge Caravans - they do the Winterhoff Hitches and I am sure they keep the friction pads - they sell online/via the phone
http://www.highbridgecaravans.co.uk/
Peter and Linda from Plymouth
Hobby 540 UK Delux
Blue Fiat Ullysse 2.0
(Much loved Synergie eaten by lorry on M5)