I didn't see any any names on the roller parts. The roller diameter is ~ 1 1/4 to 1 1/8.
If you can't find the whole roller, but you have a pair of special bolt as shown in the photos, then I can fix the wiggle problems.
Tom from SWISCO responded:
October 14, 2016
Please see our 23-081 closet door roller and let me know if this would be a good replacement option.
A professional from CA says:
October 14, 2016
The wheel looks trashed, but I think it's concave. Look at 23-070. It is the same housing with a different wheel. 23-086 is the same with a ball-bearing concave wheel. Well worth the difference.