I got rid of my Winchester 1300 (perma-lent it to the brother in law) after I broke the first action bar during a duck hunt, then the second one a couple weeks later, which left me in the middle of a Saturday hunt on the Fundy coast with no backup gun ... what I'm getting at is, I'd replace it ASAP before the second one breaks, but I guess you know that.
I bought a replacement forearm off a guy on the site here, who had a spare kicking around. I think most 1200/1300/2200/120 parts are interchangeable, with the main exception being the Defender forearms. There are two different action bar lengths; measure what one you have to make sure your replacement fits.
I love the 1200/1300/2200 series of pumps, but they are not as robust as I'd like, and difficult to shoot left handed, so I moved on, but as far as I'm concerned, no other pump works as slick or is as easy to clean.