When I try to shift from the smallest cog to the next biggest one, I have to shift three times before it moves. Click one and I see the cable tightening. Click two and nothing, and click three and then it moves. But as a result of this, I can't hit my four biggest cogs in the back.
I can manually move the derailer such that it goes to the biggest cog, so it doesn't seem like I need more cable to enable this movement. As soon as I let go of the derailer and peddle, it goes back to 4 short of the biggest cog.
What could be wrong or what could I try to trouble shoot this?