Just did this on my COE and the above answers contain the keypoints. First, make yourself a two inch long segment of the new or old rubber and slide this along the track. This will locate all the pinch points, some you won't have detected at all. Open those up with a screwdriver or other tool. I used Windex for lubricant, works great and doesn't leave a residue. I started at the upper rear open area and fed the rubber down the relatively straight rear area. This will give a feel of what it will be like. I would add that to have two people will make it go alot faster and easier. Once you get a good length in the track, you need to pull at the leading edge of the rubber while you feed new rubber at the rear. Two people do this much better.

Kent

1937 Chevy 1/2 ton
1942 Chevy 1/2 ton
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1950 Chevy COE Model 5700 ~ "Barney" ~ And more pix