A long-lost repair finally made it to the top of the list:
The original string had long since rotted out, but everything else was in a plastic bag just waiting for this occasion.
The colorful cylinders are stacks of laser-cut 6 mm disks with a 2 mm hole, held to the wire & string with a tiny dot of high-viscosity cyanoacrylate glue at each end:
The disks came from acrylic leftovers:
The motion you can’t see makes the shiny bikes much more visible out there:
The string came from dismantled badge reels providing spiral springs for the auto-retracting spools in the PolyDryer boxes.
The weight ball had a 2 mm hole filled by a wood plug which I cleaned out piecemeal with a 1.5 mm drill bit in a pin vise; a short length of wood skewer holds the new string in place.
Because the upper arms support more weight, their disk stacks need fewer disks for the same leverage. The original mobile had (at most) four 6 mm chromed plastic balls at each level, so I started with eight 3 mm disks, adjusted the stack length as needed, glued them in place, then removed the surplus disks by crushing them with a Vise-Grip.
I should rip off the design (“© otagiri 1979”) to build another with recumbent bikes.
The Smell of Molten Projects in the Morning 
