The rust is normal. The heat from the charcoal will remove most coatings on charcoal grates. You should be able to get the diameter of the grate and get a replacement.
Team: Pyle's BBQ; Good-One "Trail Boss" 60T; Homemade rig; 22" Weber Kettle w/rotisserie ring; Big A$$ Rotisserie; BGE-Small; Weber Kettle Gold, Weber OTS, New Braunfels offset smoker.
Saddles BBQ Bistro