a rear wall end 89 the roof 86 interconnects the sides 87 and ends 88 and 89 so that when the cover 80 is positioned over the base 26 the walls 64 and 84 are in substantially continuous contact about their perimeters an upper portion 93 of the passageway 90 is defined by a pair of longitudinal generally parallel walls 97 and a roof 98 the upper portion 93 extends from a first end 92 adjacent the front wall end 88 to a second end 89 adjacent the outer rib 36 of the front apparatus 37 generally along the longitudinal axis of the cover 80 a groove 81 is formed in the roof 98 of the upper portion 93 adjacent the front wall end 88 the groove 81 is generally aligned with the inner rib 38 of the front apparatus 37 in order to receive a resilient member 72 the upper portion 93 is dimensioned to receive a portion of the second cable 24 when the cover 80 is operatively associated with the base 26 the grooves 70 and 81 cooperatively define an annular groove which receives the resilient member 72 with slight interference the cover 80 is then preferably ultrasonically welded to the base.