TRACK

The guide wheel and some other plastic for the Crisper Drawers had broken. The new part arrived and only partly resembled the original. That turned out to be good news.
First, you have to remove the drawers, then the glass shelf assembly. Put the glass aside.
To remove the original support, an area of the old one that joined the part to the shelf unit above had to be broken off. Once that was removed the part came away easily.
In contrast, the replacement part easily slid into place. I reassembled the shelf and drawers easily.