broken roller at top of bifold door

The plastic is broken at the top of the roller on the top of a mirrored bifold closet door. This prevents the door from staying on the track.
I removed the 2 screws holding the bracket to the door. The roller is part of the bracket, the do not come apart. Not sure what part this is and if the roller was original "straight" or had a "ridge" as it is now. The doors were already installed when I bought my apt.
Thank you