Howdy
Smith and Wesson changed the thread on the extractor rod on their revolvers from a right hand thread to a left hand thread because of this problem. It took a while for the change to make it's way through all their products, but in 1961 the Model 10 experienced this change. This was with the Model 10-2 with the standard barrel and the Model 10-3 with the heavy barrel. It is easy for an unscrewed extractor rod to lock up the gun, making it difficult to open the cylinder. Sometimes it only takes a 1/2 of a revolution or so. Before you try loctite, try some nail polish on the threads. Just enough to keep the rod from backing out. If the rod backs out enough to prevent opening the cylinder, you can usually turn the rod just a bit with your fingers to open the gun.