pop-up slide track
I am working on my Capster pop-up refurbishment. Fortunately I do not need to replace my slide track and rollers.
Looking at what that sliding track system is now that I have it off the roof I can tell that what they used was a piece of door track and the roller assembly made for it. It is old stuff, no one has an exact replacement for it. But if you want to try find that out for yourself the keywords are door track roller.
The concept of replacing that track and rollers with drawer runners is an excellent one and would be what I would do if I did need to replace mine. But I would not use one of the expensive types with ball bearings as the outside environment is much too dirty and dusty for that. Just get the old standard kind that run on nylon rollers, fewer moving parts and less of a dirt trap.
Of if you wanted to reuse part of the original track but your wheels are gone you could use the replacement wheels made for door track. A wheel that is 3/4" diameter and 1/4" or less in thickness will fit inside the original track. But you will also want to add a couple of nylon bushings to simulate the original V grooved type of shape that helped keep it guided nice and stable along the outside face of the track. Some of the older inexpensive drawer tracks had 3/4" diameter wheels in them so that is another salvage operation possibility for replacement wheels to run inside that old door track from the 60's. But you might as well just replace the track with it as the labor will be less and the cost won't be significant.