actuating arm assembly the roller bearings are positioned at the outermost position or ends within the bore 50 of the actuating arm to provide maximum stable support for the arm the outside ends of the respective roller bearings are spaced from the respective housing wall by a distance d which in a normal embodiment is on the order of about 2 2 millimeters or 0 086 inches the height of each bearing unit raceways are on the order of about 6 millimeters thus the spacing between the end of the bearing and the housing of 2 2 millimeters provides the spacing or clearance available for bearing seal as previously described an annular seal 52 has an inner edge secured by suitable adhesive means 54 to the inner race 44 and adhesive means 56 to the outer raceway 46 this seal member 52 may have any number of physical and structural characteristics as will be described however it is preferably impervious and elastic and secured such that at home or neutral position of the arm assembly there is no torsional stress in the seal member the arm assembly 22 in the typical embodiment swings on the order of about 7 to 10 degrees to each side of the neutral or home position however in.