He bought us replacement rollers, but it was up to me to install them. Below you can see the old ones had seen better days. You might also notice the new rollers are different from the old ones. I noticed that too, but we went ahead and tried them and they worked well enough.
We also took the time to clean and lube the tracks. Once that was done, we put the doors back in place and were mildly surprised when they worked beautifully. It is a relatively simple thing, but it is SO NICE to have doors that slide smoothly. We should have done this ages ago.
Thanks for the inspiration and the parts, Dad.
One interesting discovery was the door on our bedroom was installed incorrectly so anyone could easily pick up and move the non-sliding panel and get into the house. A couple stainless steel screws fixed that problem. A nice side effect is the whole assembly is noticeably better sealed now, letting in less cold air and noise. This was a very good project.