transverse of the structure the opposing longitudinal edge portions of panels 62 and 64 have inner surfaces integrally attached to opposing end portions of respective struts 66 and 68 which comprise the base of the triangular shaped structure struts 66 and 68 are tangentially disposed and have midportions integrally attached to inner end portions of colinear axles 70 and 72 respectively the inner end portions of axles 70 and 72 are mutually spaced from one another by interposed gap 74 which provides flexibility in a direction longitudinally of the triangular shaped stucture axle 70 has an outer end portion 69 of reduced diameter for fitting into the aperture 22 in side wall 16 of shell 12 and providing an annular shoulder surface 73 for bearing against the inner surface of side wall 16 an outer end portion 71 of axle 72 has a reduced diameter for fitting into the aperture 22 in side wall 14 of shell 12 and has an integrally attached disc 76 extending radially therefrom the disc 76 is provided with a radially disposed slot 78 which may have a dog leg configuration disposed in the outer surface of disc 76 is a sector recess 79 defined by angularly disposed end walls 75 and 77 respectively thus before the housing 30 is slidably inserted into shell 12 the rotor 60 is disposed traversely therein to extend through the opposing openings 40 and 42 and the limit stop projection 58 is disposed in the recess 79 of disc 76 consequently when the housing and rotor subassembly is slidably inserted into shell 12 as described the reduced diameter outer end portions 69 and 71.