The growing popularity of cassettes in the music industry is creating a serious tape shortage. One die-hard supplier, National Audio Co. in Springfield, Mo., sees an opportunity. Photo: Blake Nelson for The Wall Street Journal Don’t miss a WSJ video, subscribe here: http://bit.ly/14Q81Xy More from the Wall Street Journal: Visit WSJ.com: http://www.wsj.com Visit the WSJ Video Center: https://wsj.com/video On Facebook: https://www.facebook.com/pg/wsj/videos/ On Twitter: https://twitter.com/WSJ On Snapchat: https://on.wsj.com/2ratjSM