You all are correct that "shaft" refers to a penis. This song is about the inability to achieve an erection. Hence, "Why can't I get it straight" and "Up until this day" As in, his penis is always able to get "UP" until the day he needs it. He is so frustrated that he wishes for Lorena to come cut it off so he wouldn't have the oh so common problem of not being able to get it up.
You all are correct that "shaft" refers to a penis. This song is about the inability to achieve an erection. Hence, "Why can't I get it straight" and "Up until this day" As in, his penis is always able to get "UP" until the day he needs it. He is so frustrated that he wishes for Lorena to come cut it off so he wouldn't have the oh so common problem of not being able to get it up.