FIG. 17 is a diagram of a closeup of a transistor against which a pin of a gantry assembly is to apply force. Transistor 1700 is locked into a corresponding location on cassette 1706 via snap features (e.g., snap feature 1702). Transistor 1700 also includes recess 1704 (which is shown to be a hole in the example transistor design of FIG. 17) through which the tip of a pin of a gantry assembly can be inserted to engage the pin with the transistor and ensure that the force from the spring-loaded pin is sustained over the transistor. FIG. 17 also shows that cassette 1706 exposes the bottom surface of each transistor to the top thermal interface layer of the thermal interface sandwich that sits beneath cassette 1706.