within inner recess 81 but engage in bend 88 of detent spring 64 to provide detents at two positions in the rotational travel of sweep cam 60 stop 89 slides within circumferential recess 125 pick plate 68 defines aperture 144 at narrow end 146 and curved slot 148 pick plate 68 is received in shallow recess 74 covering sweep cam 60 and retaining it in recess 72 pivot post 109 is received through aperture 144 so that pick plate 68 is pivotable about pivot post 109 in a narrow path of travel corresponding with shallow recess 74 curved edge 150 is received under tab 109 e while projections 109 d extend outwardly on either side of aperture 144 to retain pick plate 68 in position post 140 extends through curved slot 148 to enable actuation of pick plate 68 with rotation of sweep cam 60 as described further hereinbelow spool 62 generally includes barrel portion 152 and shaft portion 154 as depicted in fig2 24 barrel portion 152 defines slot 156 extending upwardly from bottom edge 158 mouth 160 of slot 156 may have chamfered edges 162 gear sector 164 is formed in a portion of top edge 166 of barrel portion 152 notch 168 is defined in barrel portion 152 near.