Originally Posted by
Halfast
Went through entire Park rear der adjust. No help. I really think the shifter is kaput because of the non movement on the first shift from cog 12 to 13. Next stop, the LBS?
My friend's 6600 was doing the same thing. I added some tension by turning the barrel adjuster one full turn counter-clockwise.
Fixed.
Be sure that your cable is properly routed at the derailleur and that the cable is not slipping at the fixing bolt.