Needle bar tensioning apparatus

A shifter adjustment assembly can be configured to couple to a shifter of a tufting apparatus, the shifter having first, second, third, and fourth shaft segments. The shifter adjustment assembly comprises a first body that is configured to couple to respective first ends of the first and third shaft segments. A second body is configured to couple to respective first ends of the second and fourth shaft segments. The shifter assembly comprises a coupling between the first body and the second body. The coupling is configured to releasably secure an axial position of the first body with respect to the second body along the longitudinal dimension. The first body and second body define respective complementary surfaces that are configured for sliding engagement so that movement between the first body and the second body in the transverse dimension is restricted and movement between the first body and the second body in the longitudinal dimension is permitted.