Sliding window rollers

I need to replace the tandem roller units on my Better Bilt Aluminum sliding windows purchased in 1971 because the plastic frames are starting to deform from the weight of the windows riding on them which causes the rollers to bind up.

The only markings on the windows are the Better Bilt name and logo on the latch handle.

The Brass roller/shaft parts are 3/8" dia & 1/4" thick.

The plastic frames are 1 5/8" long x 19/32" wide at the base and 11/16" wide at the top.

They are 3/8" high.

I have previously swapped the rollers from these frames with an identical part that is used as a guide on the top of these windows.

Please advise price and availability of this part, with or without the rollers.

I do not know if I was successful in downloading my photo to this message.

William