i tried the shifter without the chain on but the cable attached. it stopped on the 7th cog and the shifter would not move from 2 to 1. with the cable detached from the derailleur the shifter will go through all 8 positions. it does not lock up until i put enough tension on it to move the derailleur.
the derailleur with move out far enough to be lined up properly with the 8th cog when done by hand.
cable is attached firmly at the clamp in the groove.
at this point i thinking the shifter or the derailleur or both are toes up. maybe easier to just replace them both?
thanks - george t