Cleaning 3rd member

If they were new gears I too would be a bit more critical, these are not far off. Remember the set shown are used.
Since they ran in that way, I would leave them alone.

How would I know if they are new or used? I don't see any markings on the gear showing they are worn, unlike the pinion ring which is slightly shiny.

To correct this I would adjust/increase the backlash?