gear housing plate 62 and a third plate 64 which is substantially identical to said first plate in the preferred embodiment the first plate 60 has two shaft apertures 68 and 70 to separately receive the two driven shafts 72 an aperture 73 to receive a driving gear shaft 52 and may include an aperture 76 to pass the cable 54 or other means to operate a manual rotating means 40 first plate 60 further includes an access slot 78 extending radially from aperture 68 to edge 80 and a slot 82 extending radially from aperture 70 to edge 80 each of said slots 78 and 82 aligns with a radial slot 71 cut from the center of the respective shaft 72 to its periphery and extending the length thereof the purpose of these slots is to admit strands of a string as described further below second gear housing plate 62 includes a trefoil shaped opening 84 comprising three overlapping generally circular apertures whose centers are coincident with the centers for the three shaft apertures 68 70 and 73 of the first plate 60 the radius of each generally circular aperture comprising opening 84 is greater than the respective radius of each gear housing within said second plate 62 said gears include two driven gears 86 each of which has a radial slot 87 extending from its center to its circumference and each of which is attached to a slotted shaft 72 with the gear slots 87 in alignment with the shaft slots 71 a driving.