since OP was not saying which Chorus ( a Model name retained for Decades) we Guess ..
Old Loose Ball Yes .. Sealed cartridge or external Bearing? (But I may not be up to date) No.
I have 2 cartridge types : internal spline (mounts with their cassette lock ring tool) and external spline ..
I fitted the external spline as it comes closer to the axle & I added an O Ring before I put the crank arms on.
So , then I have another seal of the cartridge faces and the environment.