2,495. Failure to Check a Knife
Hilchos Shechita 1:25
Let’s say that a shochet inspected his knife and slaughtered with it, but he didn’t inspect it again after slaughtering. He then used the knife to break something like a bone or a piece of wood, after which he inspected the knife and found it unfit. In such a case, the slaughter he performed is valid based on the presumption that the knife was damaged by the thing it was used to break. Similarly, if a person neglected to re-inspect his knife, or the knife got lost before it could be re-inspected, the slaughter is valid.
Hilchos Shechita 1:26
If a shochet doesn’t have his knife inspected by an expert and he uses it to slaughter for himself, we inspect the knife. If it’s found to be good, we still place him under a ban. This is out of concern that he might rely on his own judgment again and then the knife won’t be acceptable but he’ll slaughter with it anyway. If the knife is found to be blemished, the shochet is both removed from his position and placed under a ban. All the meat that he slaughtered is deemed unacceptable.