This is the top roller assy for my mirrored closet doors. The doors came with the house that was built in the early 70's. One of the doors works fine, the other seems to be too high and will not stay on the bottom guide.
Upon closer inspection it appears that the set screws on both the left and right rollers that adjusts the height of the rollers is broken and cannot be turned for adjusting the door height. A new complete assembly (times 2) would be the easiest fix but if that's not an option how about the set screw and a new roll pin?
Just in case this might help: I located a sticker on the inside of one of the doors that says Canadian Pittsburgh Industries.
I'm thinking that this company might have made the glass for the doors, but not the doors themselves. Hope this helps.