1. when i wanna shift to 2nd gear (2nd biggest cog in the cassette) from 3rd gear... it's trying to skip 2nd gear and just goes on this rattling on trying to fall into gear and chain is sitting on top of 1st gear but not really locking.

2. it won't even shift to the 10th gear now. it just gets stuck on 9th gear and just makes rattling noises.

im playing with the 2 screws (high low screws i believe) right now but im not really familiar with them.

help?