I contacted Supplyhouse since it is under warranty, they think mid-next week I should receive a replacement. Local forecast is looking very cold for about a week, starting on Friday. 8 straight nights with lows below 14°F, with 5 in a row below 5°F. Damper picked the perfect time to fail.
I am still running the stove, with a clip to hold the damper open - as long as I remember to close it we should be OK.
Damn, that's a heat wave! Lows of -3, -11, -15, -15, -10, -9 and -4 Friday through Thursday here in Wisconsin.