I decided to put on the canvas top the other day. This helps to free up space on a shelf and also will help keep the dust out of the back of the box. Plus it helps to make it look like things are moving along.
I ended up using the original wooden runners that were still with the box when I got it. For the most part they were in great shape. Even retaining a lot of really nice original paint. The one runner did suffer from some rot on both ends and bugs in one spot. I removed as much dry rot as I could and then decided to use some 2 part epoxy casting resin I had. The stuff is very hard wearing. I did some pours to fill in the voids from the original rot. I also made some simple molds from steel plate I had. I then poured the resin in and let it setup before removing the plates. I then used a belt sander to do some finishing touches and blending of the resin into the original wood. This was all then painted up.
When I went to install them, I had to jack up one side of the box and then inset them in from the sides. After getting both in, I realized that they come in a left and right pair and well let just say I got my straw foot and right foot mixed up.
So jack up the box again and swap them around.