You said the charcoal grate was rusted, but, has it burned through ? If it's just rusty, it's fine, the charcoal isn't going to care. You could knock the rust off it if you want. If it's warmed, lay it on the ground and hammer it back into shape with a mallet. it's a charcoal grate, not a food grate. It's good until it won't hold charcoal anymore.