When stripping down a motor gear box assembly (or for any assembly with multiple parts and casings) take a dot punch, lightly dot each item with its corresponding part, (taking care to not damage any engineered surfaces) especially if there are multiple possible positions but the original position is crucial on re-assembly.
I post this because one of my less experienced team members has just stripped a gearbox assembly down to replace some worn parts. He did have the common sense to mark the parts but used a "permanent" marker pen, only to wash the marks off at the de-greasing station.