Dealing with broken clock -- Parts unavailable or absurdly priced

Well since you're talking about removing it, have you considered getting something like a flat piece of aluminum, maybe ⅛" thick, cutting it to fit over the hole where the clock sits? You take a Dremel or other sander and round/bevel the edges, then take a small diameter rivet and secure it on either side. If you paint it with spray enamel it should look good and aluminum and enamel can withstand the heat. Or you could get two small pieces of metal, use the rivets to secure them to the back of the material the hole is in with ½ of them sticking into the hole as a backer, then get a piece of aluminum the thickness of the material that hole is in. Trim it to fit nicely into the hole. Then rivet it to the backers you installed. Then, other than the rivets, it would be flush with what is there. And aluminum is soft enough drilling for the rivets should be easy. A coat of enamel and viola it should look pretty darn good! Cheapest/easiest way I know to do it since they want so much for parts.