Query related to revalidating cleaning procedure

Dear All,

Can any one clear my query related to revalidating cleaning procedure.

A XYZ drug product manufactured and cleaning validation performed for 3 batches, during cleaning of equipments operators observed more difficulty in cleaning with water; in fact cleaning takes 5 to 6 hours/ equipment (usually 2hr for any other product/ equipment), cleaning validation swab results are observed below 10PPM, now I want to change my cleaning procedure by using 50 water: 50 methanol as a cleaning solvent to avoid more time consumption for cleaning.

To go ahead what needs to be considered & how?
• Justifications to change the validated cleaning procedure.
• Impact analysis
• Investigations
• How analytical development Dept can help?
• Is it required to quantify Methanol after cleaning.