Lisa let me know this evening that the replacement for the broken door for the fireplace arrived yesterday. Unlike the first door, this one fit. (The first door shipped to us had the right part number on the packing list but was actually a door from a different model from the same manufacturer. The manufacturer sent us the correct door at no additional charge and is supposed to send us a UPS call tag for the return of the wrong door.) Lisa installed the replacement door and got a fire going in the fireplace for the first time this season. She's much happier now and much more certain I will be able to work from home over Christmas without freezing my fingers, Bob Crachit-like, in the living room-office. The only challenge facing us is that while the wood box (the one she painted this past summer) is full of 3/4 cord of wood, that's all we have, and it will be at least a month before we can afford to buy more, as firewood costs about $275/cord delivered.
But in any event, replacing the fireplace door (~$250) was much less expensive than buying a whole new fireplace insert would have been.