You are not the only one. A couple of years ago I spotted mouse droppings in my older cookshack. After a thorough cleaning of scraping and oven cleaner, I used a short but heavy bolt and a washer to plug the hole when the smoker is not in use. The washer was oversized and allowed me to bend it to fit the profile of the smoker floor pan and still slide over the bolt. JB Weld secured the washer to the bolt and filled in the gap between bolt head and the bent washer. Problem solved. Works well on the SI smokers too.