i had this on my passenger seat. I WD40 all the rails and anything else i could find that was linked to the seat and its ok now.
 
Just to check Ive got a small tap that I can recreate by pushing back and forth but only on the left hand side of the seat and thats the side the click/dink noise is on. Im planning on getting the seat out..the problem is I could really do with someone in the seat rocking it whilst I take a look....not easy to do though!