Stanley closet door hanger, plastic piece

I have a 30 yr old home that has stanley closet door hanger hardware throughout. The plastic part for adjustment is deteriorating with age. Everything else is fine. Where can I find the white plastic wheel that adjusts the door elevation? See attached photo:

The dial hanger for wardrobe sliding door is designated as rear or front. since 7/16' and 1/8' is so close....how do we determine if it is rear or front

re the 23-024 and 23-025 dial hanger

I have 3 rooms with bypass sliding closet doors, two double closets, one single closet (10 doors). All doors have been removed, cleaned up, painted, etc. All doors are old, solid wood, each probably 1.25 inches thick. Problem is, all the old hanger hardware was accidentally thrown out. House built in the 60's, and closets have simple, dual track for the doors, with roller hangers. How do I determine the proper hardware and offsets? Errors were made by previous owners--some doors have deep gouges from rubbing on the wrong size hangers. Thanks.