Tell your referencer that you will understand that he wishes not to answer some questions. Begin by confirming the resume. Give particular attention to dates of employment. Clarify inconsistencies immediately. Before disqualifying a candidate for inaccurate resume statements, check for a reason or misunderstanding.
People usually give their title on leaving a job.
Ascertain for what period of time the person held that position. Confirm statements made to you by the candidate regarding achievements, reasons for leaving, problems. Divorce yourself from your initial impression. Try not to set the tone of the reference by a leading statement. Take notes as you gather references.