Having trouble threading the bobbin on an old 328p Singer sewing machine. Have loaded the bobbin into it's hole but can't interpret how to link its thread to the top thread/needle. Have watched some instructional videos on the web but seems rather different (thread reel doesn't require a separate outer bobbin - it slots right into the "lower deck" beneath the foot/needle). Any help/advice/diagrams instruction manual would be greatly appreciated. Regards, Paul