How to fix 40 gallon breeder lid?

my sister bought a bearded dragon from a family a few years ago, it came with the tank and lid, the lid is extremely beat up (tears in it and burn marks) it’s held up well till now. i want to replace the screen but on the underside of the lid it’s missing a metal bar that acts like a clamp to keep the screen in place. does anyone have tips on how to purshase the single metal bar? or a website that could help me