I have a model SCO-150 crock pot. When I turned

Well stocked hardware stores have knobs that fit the heat controls on units like the Corningware slow cooker. That's either a local hardware store or a "big box" store. And Radio Shack or another big electronics parts places might, too. Notice the shaft of the control. It's almost certainly round with a "flat spot" on it. The flat spot is manufactured on the shaft of the control so the knob will have a place to "grip" the shaft and not slip.The knobs are pretty standard in the electrical industry. They're used for stuff like light dimmers and such. If you can measure the shaft, you'll probably find it's 1/4" in diameter - a standard size. Call your local True Value or Ace Hardware and explain the problem. It's almost a sure bet that they've got a solution. Make a measurement and make a call. If they've got one, go ahead and pack your cooker in with you, just to be sure. They can check the fit. One trip is all it should take. The staff at the hardware store is waiting to help you. They want you to call.