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Others have had issues where a plastic part has broken in the linkage. I haven't had the problem myself but your issue sounds like it may be it.

 

Very common for the white plastic piece to break inside the shifter. I have an aluminum replacement for $175. It won't break again!

 

On the later S types, the two 8mm headed bolts that hold the trans cable to the side of the transmission work loose and at times completely fall out. Give those bolts a look before replacing anything. The later S types also had a different shifter than the earlier S, and are much more robust.

 

I'm not the Original Poster but thanks Poboy for that tip. I'll add that to the list of service items to check! Great tip!