I need to replace the rear sight blade on my 5" 629 Classic with a lower sight blade. I was under the impression that when you remove the old blade you have to snap / break the retainer on the adjusting screw to get it to come off. You then need to obtain a new replacement screw when mounting the new blade. A call to S&W today resulted in a young lady telling me you only have to back the adjusting screw all the way out and she never heard of any other parts being needed. I would appreciate any input from someone who has changed this blade before. Thanks for any info provided!