I have a Dec 2002 date of manufacture R53 with a missing radio antenna. I bought the car used and the antenna was always been a bit loose, but recently came completely out of the car and is lost. What is left is what appears to be a solid plastic cylinder with a 'cross' or 'plus' sign. In purchasing a replacement stubby antenna from Cravenspeed I received direction to thread an insert into the car's antenna base, but that is not what I have. On realoem.com it does not show the 'plastic' solid cylinder that I have. What am I doing incorrectly? Thanks!