What you need is a new guiderod. that guiderod thingy you have there is an old aftermarket part called the Menck Impact Buffer. It was a well made and well thought out idea but never really caught on unfortunately. So, to go with your new spring, I suggest you go buy one of these while they are still in stock. Smith & Wesson Recoil Spring Guide Assembly S&W 4003TSW 4006TSW
And mothball that Menck part. No parts are available for that unit anymore.