Our old bungolow style house was painted with a latex exterior over oil base coat five years ago. The side is cement cinder block and stucco. Some spots have peeled pretty bad. We pressure washed the house and removed the peeling paint(appox. 5%). The professional at the paintstore said to remove all the latex paint. Is this really necessary or can we just prime it and paint over it? If we need to remove it, any suggestion as to how?