Front-wheel attaches to the shelf above. Where it screws in is kind of flimsy, no way to repair, had to replace the entire shelf, including the glass. Appliances Parts Pros had the best price, and it arrived quickly.
You have to swap the metal brackets from the old to the new shelf (2 brackets x 5 screws), and reuse the old wheels as well. One thing to note, the holes for the screws and for the wheels are not threaded. The screws cut the threads. Use caution when putting in the screws and wheels to make sure they are straight.
Total repair time about 20 minutes.