of the panel 15 the brackets 27 having openings 27a permitting them to be secured by suitable screws 28a extending into openings 28 provided in the panel 15 the brackets 27 further have upstanding plates 27b with openings 27c bushings 30 are provided for the rotatable pulleys the pulleys being protected by a pulley cover plate 31 with openings 31a aligning with the openings 27c the bracket assembly further includes bolt fasteners 32 which pass through the openings 31a bushings 30 and openings 27c and nuts 32a for retaining them as fig1 further discloses the pulley support brackets 27 include rearwardly extending plate portions 33 with openings 34 through which the upper ends of mast 16 extend to maintain the plumb of the masts and panel 15 it will be noted that each of the counterweights 25 is recessed as at 35 fig1 to receive the cables 22 and is further generally cylindrically vertically slotted as at 36 to receive the masts 16 and guide thereon in up and down movement to facilitate aligned sliding movement the counterweights 36 are provided with slots 38a for receiving linear weight glide bushings 38 which mount in slots 38a provided in the masts 16 two or three such slots 38a and glides 38 may be provided the telescopic guide assembly 17 includes for each mast 16 an inner tube generally designated 39 fixed to the bracket 18 a mid tube generally designated 40 and a plunger assembly generally designated 41 which telescopically connects each mid tube 40 with an inner tube 39 the mid tubes 40 are slidably received within the tubular masts 16 the inner tubes 39 are slidably received within the mid tubes 40 and the plungers 41 are.