This Christmas, I got a Singer Prelude. I was threading the machine and trying to raise the bobbin thread, but was not able to. The upper thread would snag on something and the bobbin thread would not raise. I followed the manual precisely but I must have screwed up somewhere. From the research i have done it seems like i have to re-time the sewing machine. I am beginner when it comes to sewing so i have no clue what is wrong and how I can fix it. Please help.