I had several expresses come out of the winter with a channel or two always on. For all but one, I changed the Triacs and the problems went away. For my last express, I swapped in a new Triac and opto chip but the channel is still stuck on. I suppose my new triac could be bad as well but that seems unlikely. Is there another failure point that can leave a channel on? At last resort, I will try another Triac, but these are a beast to swap out!