The positioning finger shouldn't be it, but it's worth looking. Make sure that the finger is where it belongs, like in this pic (and thanks to Candace for posting it first so I could refer to it.
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http://www.april1930s.com/html/bobbi...___needle.html
Also double check that the bobbin case is completely snapped into place. Sometimes it seems like they are but they're not....
If none of the above posted solutions work, please check the timing and let us know. You don't need to take it to a repair (wo)man for this.
I can post an image if necessary, but it's pretty simple.
If you watch Dan's avatar, you'll see that when the needle is down, the hook is just about behind it, but not quite. To be timed right, the needle will be on its upswing as the hook ends up behind it to catch the needle thread.
If you remove the faceplate on the machine, and turn the handwheel so that the needlebar is in the fully down position, you'll see 2 lines on the top of the needlebar.
If you turn the handwheel further, until the needlebar has covered the top line, and is just about to cover the second line, when you look at where the hook is, it should be directly behind the needle. If it's a little further ahead or behind than that, this means the timing is off, and you may find that it starts to stitch weird.
If the timing is off, please let us know, and I'll post a couple of pictures on how to time it. It's also not difficult. It's one of those things that sounds scarier than it is... like adjusting bobbin case tension.
Just patience required.