My approach would be to cut a small, thin piece of sheet metal not quite as wide as the tab and about 1" long. Then epoxy the tab to one end of it so that the tab just sticks out a little from the end of the metal piece (if you can cut one end of the piece to the same shape and dimensions of the tab, so much the better). Once the tab is epoxied to one end of the piece, drill out the hole through the piece to match the hole in the tab.
Then, trial fit the other end of the piece under the frame so that the tab sits flush with where it broke off. You may need to do a little grinding with a Dremel to make the tab fit flush against the frame.
Once you're satisfied with the fit, just epoxy the other end of the piece to the underside of the frame and you should be good to go.
