Agate stone bearings don't wear, just get dirty and they last multiple lifetimes.
They probably just need some cleaning along with the posts they "free float" on -
https://www.thehighroad.org/index.php?threads/best-balance-scale-available.864676/#post-11415433
How to clean/tune/zero your 5-0-5/10-10 beam scales:
- Remove the bearing covers with a Phillips screwdriver (see pictures below)
- Make sure the posts the agate bearings free float on are clean
- Clean the agate bearings, especially the "V" notches with alcohol
- Re-install the covers
- Clean the knife edges
- Level the bench surface using a bubble level at 90 degrees
- Turn HVAC/vent off and close the window/door to the room as any ambient air movement will affect scale reading/zero
- Place the powder pan on the pan support
- Set poises to zero
- Adjust the leveling foot so the pointer is at the zero line
Ohaus 10-10 knife edge on agate stone bearing with cover on and off
RCBS 5-0-5 post that agate stone "free floats" on
New to me Dillon Eliminator (Built by Ohaus to 5-0-5 specs) clean up and zero -
https://www.thehighroad.org/index.php?threads/new-to-me-dillon-eliminator-beam-scale.913581/
Agate stone bearings "free float" on round posts and any dirt/residue/build up that can interfere with free movement of the agate bearings can bind the knife edge of the beam and affect return to zero.
Here are the dirty agate bearings and covers
And dirty posts
After cleaning with alcohol
Clean agate bearings and covers
Knife edges cleaned
After cleaning, scale verified Troemner 50 grains down to 0.5 gr check weights and returned to zero consistently