HI, there are a few reasons for this. Make absolutley sure your needle is threaded correctly. (I've been sewing for years and this sometimes happens.) Next, make sure you have the correct tension for the thread, and the material you are working with and of course the correct size needle and not an old one.
Sometimes the thread is old and it minutely frays and knots, or the needle is blunt. And finally, make sure there is no thread tangled underneath. Hope this helps.:-)
Check how your thread is coming off of your spool of thread. If it is older thread it is wound on the spool differently than a modern spool of thread. The older types of spool were would to pull off of the spool from the side. The newer thread is wound so that the tread needs to come off the spool from the top.
There is between two and four screws on top of the machine. Remove them. Pay attention to the bobbin winder. You may need to move it in order to get the plate to be released.
Quite probably there is a bit of oil on the belt somewhere that has oil on it.
Check with a technician if the sound does not go away with a bit of time.
Your needle tension would depend on your size needle, size thread, and thickness of material. Try experimenting with tension up or down to see how that works. :-)
