how to fix drive gear on a brother vx-1125 and get it timed again?

Hi
My machine stoped winding my bobbing round. so after some stripping of the machine, have found that the screw came out of the drive gear. (which was white with little teeth) None of the gear teeth look broken. Have put it back in but have no idea where the gears should sit in relation to the bobbin? I have fixed cars before with my husband and this seems to be a bit like timming the car with a cam belt. If only there was a book for this. I could do with some one telling or showing me pics of where it all should be. I feel I am so close i can not give up.! Please help me :-)