An apparatus, comprising: (a) a body comprising a knob ; (b) a shaft assembly extending distally from the body, wherein the shaft assembly comprises: (i) an outer tube , (ii) a proximal inner tube member , (iii) a distal inner tube member , and (iv) an acoustic waveguide ; and (c) an end effector , wherein the end effector comprises: (i) an ultrasonic blade acoustically coupled with the acoustic waveguide , and (ii) a clamp arm , wherein a first portion of the clamp arm is pivotably coupled with a distal end of the outer tube , wherein a second portion of the clamp arm is pivotably coupled with a distal end of the distal inner tube member ; wherein the outer tube is configured to removably couple with the body and the distal inner tube member is configured to removably couple with the proximal inner tube member such that the outer tube , the distal inner tube member , and the clamp arm are configured to removably couple with the body and the remainder of the shaft assembly and end effector as a unit; wherein the knob is operable to rotate the shaft assembly and the end effector about a longitudinal axis defined by the shaft assembly; and wherein the knob and the outer tube comprise complementary alignment features that are configured to restrict insertion of a proximal end of the outer tube into the body based on an angular orientation of the outer tube relative to the knob about the longitudinal axis. (a) a body comprising a knob ; (b) a shaft assembly extending distally from the body, wherein the shaft assembly comprises: (i) an outer tube , (ii) a proximal inner tube member , (iii) a distal inner tube member , and (iv) an acoustic waveguide ; and (i) an outer tube , (ii) a proximal inner tube member , (iii) a distal inner tube member , and (iv) an acoustic waveguide ; and (c) an end effector , wherein the end effector comprises: (i) an ultrasonic blade acoustically coupled with the acoustic waveguide , and (ii) a clamp arm , wherein a first portion of the clamp arm is pivotably coupled with a distal end of the outer tube , wherein a second portion of the clamp arm is pivotably coupled with a distal end of the distal inner tube member ; (i) an ultrasonic blade acoustically coupled with the acoustic waveguide , and (ii) a clamp arm , wherein a first portion of the clamp arm is pivotably coupled with a distal end of the outer tube , wherein a second portion of the clamp arm is pivotably coupled with a distal end of the distal inner tube member ; wherein the outer tube is configured to removably couple with the body and the distal inner tube member is configured to removably couple with the proximal inner tube member such that the outer tube , the distal inner tube member , and the clamp arm are configured to removably couple with the body and the remainder of the shaft assembly and end effector as a unit; wherein the knob is operable to rotate the shaft assembly and the end effector about a longitudinal axis defined by the shaft assembly; and wherein the knob and the outer tube comprise complementary alignment features that are configured to restrict insertion of a proximal end of the outer tube into the body based on an angular orientation of the outer tube relative to the knob about the longitudinal axis. <EOS>