Hi Bob and Woz,
We manufacture the Blade Tech Knife sharpener and I can 110% guarantee that it will not damage any knife you put through it whether it's a cheap knife or expensive as long as it's used correctly. If you're still having problems with the knife and/or the sharpener then please, by all means send it and/or the knife back to us mate. We'll sharpen your knife up for you and see if your Blade Tech if defective. If it is we will simply replace it and return the knife and replacement sharpener. If the sharpener is fine we will resharpen your knife and return the knife and the origi