I have a Brother PC-420PRW, and for the most part i really love this machine. but, there is something that irks me...why is it, that the bottom thread never looks as neat as the top? i mean, if this is normal, im ok with it, but i tried everything. i made sure the needle/thread combo is right. it is not terribly bad, but it always seems like it's never as nice as the top. maybe i'm not setting something right...anyone else have this problem who has this particular machine?

There is often a teensy tiny screw on the bobbin case. if you tighten that screw just 1/4 turn, it may fix this problem. I've had to do this on my Janome machines and once done, it stays unless/until you tweak it again and once I got my stitches perfect, I never touched it again. It does require a very tiny screw driver but give that a try!