is contoured and includes an outer surface 35 the drive pin 26 is positioned within the insert opening 34 the outer surface 35 of the insert member 33 is spaced from the centerline of said door shaft 11 a distance approximately the same as the outer surface of the drive pin 26 is spaced from the centerline of the door shaft 11 when the tape 30 is folded around the surface 35 of the insert member 33 the surface 35 ensures that the tape is folded so that it is approximately concentric with the shaft 11 and the tape 30 has a generally circular cross section because the tape 30 is continuous as it is folded a double layer of the tape is positioned around the door shaft 11 during each rotation of the door shaft 11 this double folding of the tape is important and ensures that tape quickly moves from the fig3 position to the fig4 position where the tape 30 has a greater effective radius and therefore provides a greater counterweight torque force the continuous flexible tape 30 includes a second portion 37 which is connected to a counterweight 38 in the present embodiment the counterweight 38 comprises a plurality of metal weights 39 which are retained in alignment by a longitudinally extending bolt 40.