23-028 with metal rollers?

My mirrored sliding doors appear to have 23-028 roller assemblies. My long-standing problem is that they have a stick/slip action but once enough energy is exerted to get them rolling, they glide easily. Dry or oily lubricants are ineffective at removing the static stick condition. I'm thinking may be wheels become slightly flat (plastic cold flow). Do you have concave wheels made of metal? The adjustable inner assembly was easy to remove but the entire assembly may not be (it's over 25 years old); however, I am prepared to buy entire new assemblies, even with plastic rollers if metal ones are not available. My goal will be to extract the new sliding part and replace it in the old fixture. Please give me a recommendation. Thanks. Allan

Paul, Your questions triggered my imagination. I think I solved this long-standing mystery. The problem seems related, not to the bottom rollers but to the top guides. They are made of vinyl and after applying a bit of grease, ease of rolling is vastly improved. The part in the photo definitely feels dirty/sticky. I don't see anything like it among your replacement part offerings. Do you have any suggestions? As a minimum I will clean all four, lubricate and reinstall but new ones would be better.

Thanks.

The width of my guides are ~1 1/2 inches. The track width is about 1/16 wider. The length is ~2" but could be longer without any problem. The old ones are definitely improved with clean up but I can see the old stick problem will resurface soon.