A method and apparatus for removing or inserting a mutator shaft from a scraped surface heat exchanger assembly comprising a split shaft design to form a plurality of mutator shaft segments. Each shaft segment contains ends further connectable with one another and may be further retained via a drive pin assembly preferably comprising a plurality of drive pin mounting screws and a drive pin. The shaft segments and drive pin assembly may be further sealed to provide a sanitary working environment particularly suitable for use in the foodstuff industry.