Replace it. It is safer to get a new one than to chance ruining this one or your health with chemicals. They are cheap enough that what you would spend on trying cleaners would cover the cost.

Replacing the toaster oven is one answer, but, have you priced them lately.

Today I went to several stores looking for a normal size toaster oven. Many were available but most did not have good ratings from users and were too large. The price of a toaster oven these days is high, many in the $60, 70, 80, 90 and over 100. Most are too large for a small area. I checked at Costco, Macy's, Khols, Target, TJMax, then finally at Wal-Mart.

Finally went to Wal-Mart and they had a Proctor Silex 31120 that many people said was good on reviews. Believe it or not the price was $18.00. It is still in the box, will try it later today. Just hope it is not a lemon that was returned. The box was still in good shape with what looked like original taping.