After removing the assembly from the car by taking out the three bolts (or two depending on what you drive) there are covers over both sides of the reel and how the first is removed is pretty important.
If you are very careful you can remove the cover from the spring side without the spring going sproing. Slide the cover to the side while holding the spring in the small spring pan with your thumb, or in this case, Art’s thumb. When the cover is off disengage the spring from the center shaft slot. Then carefully lift the pan with the spring in it out of the assembly and set it aside for reassembly later. I placed a large wrench on the spring to keep it in the pan while I worked on other things.
The cover over the gear side of the assembly can be removed without fear of things popping out. There are several circlips to remove so the gears can be removed and a circlip that holds the shaft in the assembly. With the circlips and gears removed from this side, including the clip holding the center shaft in, pull the shaft out from the spring side. There is no need to remove the clip from the spring side.
Take note at this point as to how the shaft, stop pin and belt material are assembled. The stitched side of the belt has to be reinstalled in the same configuration for the belt to work as designed.
Paying attention to how the detail pieces are sewn into the belt material, transfer them over to the new 8 foot 6 inch piece of material. The end flaps are 3 inches so the final length of the belt ends up being 8 feet after the sewing has been completed. Take care to ensure the flaps are folded in the same orientation as the originals and the hardware is also properly oriented.
There had obviously been water inside the assembly and the center shafts and stop pins were rusted on both. The wire wheel and some spray Rust-Oleum cleaned them up. Art recommended not using any kind of lubrication so I did not and agree that none is needed if all parts are clean and in good condition.
Re-assembly is of course in the reverse order. Make sure the hardware is on the belt and properly oriented. Place the new belt on the shaft as it is fed through the housing from the spring side making sure the sewn flap is back on as it was taken off. Replace the pin that keeps the belt from spinning on the shaft. Replace the shaft circlip, all gears and other circlips. Check the picture to see if it looks right and replace the cover.
The spring side is simpler but more risky due the tendency of the spring to slip and become something that looks like it was never round. Place spring and pan back on the shaft and maneuver the end of the spring back into the shaft slot. Carefully install the cover and you are done with reassembly and ready for reinstallation.
Place the bolt attach hardware over the holes and bushings and tighten. If everything is as it should be the belts line up with no twists when fastened and retract when not fastened. If the belt is twisted, take it all apart and reposition the belt in the reverse as to how it was put on the center shaft.
So with Art’s motivation to get past my fear of messing it up instead of fixing it the seat belts are now in very good shape and work as they should, success. As a side note I found gray belt material on ebay for $5. The original material was black but the gray looks pretty good to me.