Upon unscrewing those two screws completely, the plastic housing should fall out. If the wheel was already falling out, then the clip is what is needed.

This red clip belongs on the end of the piece highlighted in orange. Once broken off, it may be advantageous to replace the whole unit, but with some bending of this metal ring, it can be maneuvered back onto this metal piece. If this is not an option, replacement is the proper route here.