Clarks ACE Hardware said:We have replaced about two dozen refractory access covers under warranty out of about 100 2n1's sold. We have yet to have anyone break one a second time. They could have definitely been designed better, but I believe breakage can be avoided.
FWIW, we have burned 3 different Defiant 2n1's in our showroom with at least 10 different people loading/operating the stove and have yet to break one of these covers ourselves.
That is about 24% in terms of failure!! Not too good rate me thinks!