the axis of center post 31 so that when latch 43 is in the unlatched position in axial alignment with center post 31 ejector spring 33 forces ejector bushing 34 and bobbin 36 seated thereon outwardly from bobbin case 25 so that bobbin 36 may be grasped and removed and the outer end of bobbin ejector bushing 34 is forced against the end of latch 43 any movement of latch 43 will compress ejector coil spring 33 and thus movement of latch 43 is resisted when latch 43 is placed in position at right angles to the axis of center post 31 in a latched position as shown in solid lines in fig2 and 5 a flat inner face of latch 43 bears against the outer end of bobbin ejector bushing 34 compresses ejector coil spring 33 forces bobbin ejector bushing 34 to remain operably inserted in bobbin case 25 and bobbin 36 mounted on ejector bushing 34 is thereby rotatably constrained in operable position the pivot end of latch 43 is shaped and proportioned and pivot pin 42 located i e pivot pin 42 is located far enough from the inner face of latch 43 and that inner face extends beyond the axis of center post 31 so that bobbin ejector bushing 34 is forced against the outer end of the inner face of latch 43 any movement of latch 43 compresses ejector coil spring 33 and movement of latch 43 is resisted as shown in fig5 another means for biasing latch 43 in the latched and unlatched positions can be provided by a flat spring 44 attached as by brazing to the outer face of latch 43 having a free end forming.