I've notice that my seat in my 97' Jetta GLX VR6 is loose. Apparently I've narrowed it down to a small plastic sleeve that rides along the track that moves the seat forward and back. I think that piece has broke and now is no longer on the track making the seat loose. The mechanic told me I'm safe but I want to replace this part. Does anyone know the name of the part and where on earth I can find it?