Trying to adjust gears on my Freego Eagle but can't seem to get lined up properly. It has a Shimano Tourney TX rear mech and a 7speed block. The lowest 7th being a large cog (easy to pedal should battery run out). I can get it to fifth ok no prob but into sixth is rattling and out of line as if it has gone too far. Unfortunately the low screw doesn't seem to do anything. Any ideas what I am doing wrong. It was working but took wheel off to change tyre. I understand that the Tourney is a cheapo and wondered if I may be better to change it, possibly with the block to give a higher top gear.
regards
regards