I don't believe Ruger makes the SP101 in .38Spl with the 3-1/16" barrel anymore. I've got one that is a first year production and I love it. Does yours have the factory spurless hammer or did someone cut it off?
Lots of people like to do home gunsmithing. Especially on a Ruger double action, because it is so easy to take apart. IBOK is a popular guide available on the internet forums for doing your own gunsmithing. This can have mixed results. I've rebuilt many of these guns that had problems. Ruger used to sell me parts like hammers, triggers, cylinders etc. But those days are long gone. Now if you have a gun that has been buggered up by a backyard "action job" the gun must be sent back to Ruger to have all the bad parts replaced. Any competent gunsmith can smooth out the action on a Ruger DA. Or you can slick it up yourself with lighter springs and simply firing the gun a few hundred times. But I'm always leery of a gun that has had the internal parts "stoned" unless it also comes with paperwork from somebody famous.