rollers for circa 1950s Geneva metal kitchen cabinet drawers

The plastic/nylon rollers broke. They are 1 1/8 inch in diameter and I was so excited to see that Swisco had 1 1/8 inch plastic rollers and ordered them. However, there is a problem in installing them because the old rollers were attached by welding. There is still a round welded screw in the rail to which the original rollers were attached. How to get it out??? The Swisco part has a raised portion attached to it, so it won't fit unless welded portion of rail is removed.