Originally Posted by Lori S

Check to make sure you have the bobbin loaded correctly , it will make that sound if the bobbin thread has jumped out of the small tension bar located in the drop in bobbin case at about the 7 o'clock postion. When you thread the bobbin thry the bobbin tension it should "click" the thread into place. Also it only takes viking bobbins, they should have as H printed in the plastic. Viking never made a metal one for this machine. That H should always be facing you. when you wind the bobbin and when you drop in in the bobbin case.
That "bobbin case " is removable and I highly recommend you do periodically take it out, lint does collect under that case. You need a small hex screw driver to remove the one screw ( some time a dealer will replace that hex screw with a regular flat head screw. It can be a bit tricky at first to figure out how to get that bobbin case out, and back in but once you do it a few times you will gat the hang of it. It helps if you use rubber fingers ( like the bank tellers used to use) . Mine can with a rubber finger cover, your nay still have it.
Do check and make sure the needle is pushed all the way to the needle stop. Also change the needle.
Hope this helps.