Good advise both times. WD40 is not my first choice. Penetrating oils have been around since liquid wrench first came out somewhere in the first half of the last century. I still like it best, but there are a lot more choices today. Just give it time to work. I like to use a brass hammer, but any semi hard faced hammer should work. They do the same job as the wood, but with a lot less fuss. Be sure to clean up the shaft before reassembly and lubricate with light oil like 3 in 1 or sewing machine oil. Just for the record, WD40 is not a true oil, but it does do a credible job of lubricating on short term basis. It will evaporate in a few weeks.