the bobbin has little to do with thread pick up.... even if it was way to skinny, you would think the bobbin case would hold the thread in the correct position and then the Hook would grab the thread on its way around.... take the bobbin and the case out and make sure the actual hook is coming around ...and that it looks to be " in time" with the needle position and the scarf on the needle is in the correct place...and that your needle thread is coming from the correct side of the needle ...