first idler gear 44 is limited to movement in a first arc 54 which is centered about the axis of the drive gear 24 the second idler gear 46 is limited to movement in a second arc 56 which is centered about the axis of the driven gear 26 this arrangement serves dual purposes first since the first and second idler gears 44 46 are constrained to have a fixed distance between centers their movement relative one another can be predicted therefore the idler gears 44 46 will not separate or jam one another second by constraining the first and second idler gears 44 46 to arcs 54 56 centered on the drive and driven gears 24 26 it is ensured that the idler gears 44 46 remain in constant contact with the drive and driven gears 24 26 this setup is important to ensure constant meshing of teeth between adjacent gears even as wear of the teeth occurs the adjustment member 42 is connected to base plate 52 to transmit the necessary force to ensure contact between the teeth of the idler gears 44 46 and the drive and driven gears 24 26 even when the drive 44 and driven 46 gears are new variations in manufacturing will result in some amount of backlash between the gears the adjustment member 42 transfers a force 38 either compressive or tensile onto the base plate 52 and thereby to the idler gears 44 46 when a force 38 is applied to the adjustment member 42 the first idler gear 44 is forced into contact with either the leading or trailing edge of the drive gear 24 depending on whether the force is tensile or compressive and whether the drive.