Originally Posted by zacster

This is what I hate about indexed shifting. Everything should work, but even the slightest deviation on a part will cause issues, and then try finding the problem. In your case, you have assembled this group on ebay, so there is no guarantee that everything is in full proper working order. Is the cassette spaced properly? Is the hanger bent ever so slightly? Is the chain the proper width? Is the wheel straight? Is the cassette straight? Is the frame straight? Are the cables all dressed properly? Is every one of those 30 parts in the shifter to spec? And maybe there are different vintages of 10sp that you're encountering since you bought it piecemeal.

And you dismiss the possibility of the hanger being bent, but did you check? It is quite possible that it is bent slightly, and the other groupset you used wasn't as fussy about it. I know that Campy is. I bought the Park DAG2 because I could see that mine was out of alignment and shifting on my Chorus group was never precise. Now I get click-click-click shifting with no slop at all.