Originally Posted by gyozadude

Here's a tip:

1. Search on the bike forum for index rear derailleur adjustment for the basic concepts, which it sounds like you're trying.

2. Tip: On your particular setup, you start with shifter at top gear (7), and chain on the smallest cog, and RD cable slack. BUT, UNSCREW out the the tension adjuster barrel. 4 - 5 complete turns to extend the housing.

3. Tension and fix the RD cable to the derailleur, and then shift to 2nd smallest cog (speed 6 on the indexed shifter).

4. If it's like before, it should go to 3rd cog. Now screw in the tension adjuster barrel until the chain drops to 2nd cog.

5. Do final tightening of cable clamp bolt, adjust H-set screw, and then slowly shift from 7th to 1st gear. Adjust L-screw.

Done.

The problem you're encountering is that the 1st cog on an indexed RD system is often using the H-limit set screw as a stop and the cable should be secured only with fingers (without 4th hand tool), and the design counts on a known degree of slack in the cable initially because the shifter picks up more cable on the very first click.