Replacing a hazardous solvent in a cleaning process

Our parts cleaning process uses a chlorinated solvent that is coming under stricter regulation. Workers also complain about the smell despite extraction. We are testing aqueous cleaning and modified alcohols as alternatives.

Aqueous cleaning works for most parts but requires longer drying and leaves residues in blind holes. Modified alcohols perform better but need closed equipment. If you substituted a hazardous solvent, how did you validate cleaning quality and manage the investment?