Dan nailed it, buy new. I buy a new one every year or two. I like the wally world black and deckers, 7.95 on sale. The other regular fish cleaning brands are okay but not 3 0r 4 times better. I keep two b and d knives for when electric is available and keep two other brands for battery use when the stations are closed. Usually wear out the b and d ones within a year or two and generally get 3 years out of the battery ones.