A valve actuator assembly comprising a spring housing, an actuator stem extending at least partially into an interior volume of the spring housing and a guide member coupled to a diaphragm plate to stabilize the actuator stem relative to the spring housing, wherein the diaphragm plate further comprises: a top surface, a bottom surface, and a stem projection that extends downwardly from the bottom surface; and the guide member further comprises: a top wall disposed at a first end of the guide member, the top wall extending in a direction normal to a longitudinal axis, the top wall having a center aperture that receives the actuator stem such that the guide member is prevented from displacing relative to the actuator stem in a direction normal to the longitudinal axis; and a side wall extending along the longitudinal axis from the top wall at the first end of the guide member to an open second end of the guide member, wherein the side wall has an outer surface, and a portion of the outer surface of the side wall is adapted to engage a portion of an inner surface of the spring housing to limit displacement of the actuator stem in a direction normal to the longitudinal axis; and wherein a first end of the actuator stem is coupled to the stem projection, and the center aperture receives the stem projection. a top surface, a bottom surface, and a stem projection that extends downwardly from the bottom surface; and the guide member further comprises: a top wall disposed at a first end of the guide member, the top wall extending in a direction normal to a longitudinal axis, the top wall having a center aperture that receives the actuator stem such that the guide member is prevented from displacing relative to the actuator stem in a direction normal to the longitudinal axis; and a side wall extending along the longitudinal axis from the top wall at the first end of the guide member to an open second end of the guide member, wherein the side wall has an outer surface, and a portion of the outer surface of the side wall is adapted to engage a portion of an inner surface of the spring housing to limit displacement of the actuator stem in a direction normal to the longitudinal axis; and wherein a first end of the actuator stem is coupled to the stem projection, and the center aperture receives the stem projection. a top wall disposed at a first end of the guide member, the top wall extending in a direction normal to a longitudinal axis, the top wall having a center aperture that receives the actuator stem such that the guide member is prevented from displacing relative to the actuator stem in a direction normal to the longitudinal axis; and a side wall extending along the longitudinal axis from the top wall at the first end of the guide member to an open second end of the guide member, wherein the side wall has an outer surface, and a portion of the outer surface of the side wall is adapted to engage a portion of an inner surface of the spring housing to limit displacement of the actuator stem in a direction normal to the longitudinal axis; and wherein a first end of the actuator stem is coupled to the stem projection, and the center aperture receives the stem projection.