It is best to have tuners that do not have a lever under the tailpiece. However, if your instrument is equipped with this kind of tuner, make sure that the tuner(s) on your tailpiece are adjusted, so that they do not touch the top of your instrument. If they touch, they will scratch your instrument and interfere with proper tone production. Adjust the tuners, so that they are at about the middle of their range, so that you may adjust your strings up and down easily. If the tuner is hard to turn, remove the screw top, and apply the smallest bit of vaseline or lithium grease to the screw threads.