Thanks for posting pix of the entire set. Please forgive my directness, but I would consider either returning the bass or invest in a new set of reputable tuners. The design flaw of narrowing the worm shaft at that point will mean they will all break eventually from constantly taking all the torque load from tuning on the narrow part, instead of the load being distributed the entire length of a worm that has a consistent diameter, like a Fender standard, a old-fashioned Schaller type elephant ear tuner, or a Hipshot of whatever model, from vintage repro to Ultralite.