Make sure that all of the mechanisms are clean, well lubricated and move freely before you begin any adjustments. When replacing cables and housings it is essential to ensure that the housing ends are cut squarely and ground or filed flat and that the appropriate ferrules are installed and that all components are seated firmly. It is also critical to replace the lower loop of housing which goes to the derailleur with new housing of the correct length, again with proper ferrules.

After ensuring that the derailleur and hanger are straight, go through this procedure from start to finish without skipping any steps: http://www.parktool.com/blog/repair-...nts-derailleur Be aware that the adjustments need to be done in small increments; 1/4 turn or less may make the difference between lousy and perfect shifting. Be systematic, stop find out why and fix the problem before proceeding if any step cannot be done correctly as each step's success depends on the previous ones being correct.