no name bare aluminum sliding rollers/axles bad

Many houses in the Reno, NV area have these unbranded aluminum sliding windows. The rollers and/or axles in most of our house are shot. With some effort I could remove them, they are probably original.

Looks like the axles pull out on one side, or the head of them wears out because it serves as a guide when a nylon guide wears out or breaks. The axles are almost exactly 2cm long. The axles are 4mm in diameter and the wheels are about 16mm in diameter, probably worn a bit appear to be aluminum maybe?

I'd like to replace wheels, axles and the nylon guides as well. Sending two photos of a window that works OK and one where the axle has pulled out and bent and the wheel is not really functional.