I was given a lovely 40# galvenized metal feeder. However, the bottom pan is covered with orange rust. The main cylinder is fine, clean & rust-free except for the bottom inch on the outside. The bottom pan is fine on the underside, bright shiny metal! But the inside of that pan, the part from which the birds eat, is the part that is rusted the most. Can I still use it? As is? Should I try to treat the rust first? How? Steel wool, WD-40, Rust-O-Leum spray paint? OK, I'm out of ideas, what do you geniuses suggest?