An apparatus comprises a body and a shaft assembly. The shaft assembly is configured to couple with the body such that the shaft assembly extends distally relative to the body. The shaft assembly comprises a tubular member, an acoustic waveguide, and a guiding member. The acoustic waveguide is operable to selectively couple with an ultrasonic transducer assembly. The tubular member is configured to insertingly receive the acoustic waveguide. The acoustic waveguide comprises a guide feature. The guiding member is configured to engage the guide feature of the acoustic waveguide and thereby orient the acoustic waveguide in relation to the tubular member.
