I have a le Cresuet dutch oven.. for the past 18 years I would put my meat in this magic pan and it would FALL OFF the bone or you could cut it with a spoon .. but this past year.. all the meat is coming out tough.. including yesterdays corn beef which i cooked at 275 for about three hours and it was at 170 temp when i took it out.. the taste was great but the meat again was tough.. what is going on? please please help me.. this was covered in water.. I don't use a grate to put my food on.. I have used one in the past. .but this was what i saw on AMerica's test kitchen.. but other beef roast are tough tough tough. no more touch it and it falls apart.. has my pan gone bad?