I have read your thread from the start, I don't want to tread on anyone's toes here but as an armature polisher you should have started with a flat wheel that you put in the drill then used wet n dry all the grits as you did use a little autosol this will help.I build show winning custom bikes so nobody start prissin me off as if I am an armature because I ain't, my polisher can do a plenum in 1 hour flat 50 quid, and he's a proffesional, he specialises in this sort of thing and all the edges inside were the bolts go all nice.If you keep at it you will get there so don't give up.You just started badly but it seems as if you have got through the worst bit now