A sealer for a sample testing instrument is disclosed that cuts and seals a fluid conduit that connects a test sample device with a fluid receptacle containing a fluid sample. The sealer includes an enclosure and a protective shield to protect a user or technician from contact with the cutting element assembly in the sealer. The cutting element assembly includes a spring-loaded element that engages the test sample device and holds it in a fixed position while a cutting element (e.g., hot wire) cuts the fluid conduit. A motor driving the cutting element assembly is positioned at an angle having both vertical and horizontal components, whereby adjustment of the motor firmware allows for adjustment of the position of the cutting element relative to the instrument in both horizontal and vertical directions.