Instruction: Answer the given question using the supporting document.

Input:
Question: Does it scratch knife surfaces?
Document: Nice edge on knives....but wear is rapidly apparent on draw-through surfaces. Nevertheless, does a good job on knives that are reasonably well made.
Other knife sharpeners don't work well. This one does. Follow the directions and your knives will be sharp and easy to use.
The sharpener works okay. I wish the knife edge was a little more sharp.Over all I would order again
Does an excellent job. Can recommend it to anybody who cuts meat.As others have said, be careful with your fingers once you have usedthe Wusthof to sharpen the knife.
I have tried many different knife sharpeners over the years and this is the best I have ever had. My knives only need a touch up by the final setting to stay like razors.
Good knives don't do you much good if you don't keep them sharp. This does the trick quickly and easily. I feel like I am using a brand new knife every time! !
Same thing for my Wusthof steak knives. It is great to have these little knives slice through steak like hot butter, especially with all the abuse they get constantly cutting on people's plates.It's a bit pricey, but worth it. After all, if you take care of your Wusthof's, you'll probably never have to buy another knife in your lifetime.
I recommend watching the demo and carefully reading the instruction sheet.Use some discretion with the first wheel - it is best for deep reshaping of the knife edge, like if your knife has the sharpness of a butter knife after years of slamming the edge into a cutting board. If you only have some small dullness, try just the second wheel (then strop).
I then called customer service to tell them it was a sharpener issue (not a knife) - and was told that they don't supply parts and that my only options were to package and ship the whole sharpener assembly back to either Wusthof or to Amazon. The missing rubber foot is at most a $0.50 cent part that simply pushes into place, and I think it ridiculous that their fix to this problem is a complicated and expensive re-packaging and shipment.
Very nice sharpener. On the positive side very easy to use. Sturdy. I just used an old fish filet knife as my first test knife. No problem at all. Just placed it in and down and pulled it backwards all at the same time. Then I did my entire set of Westhofs. I don't know what any fuss from other reviewers is about on using the thing. Be careful about checking the edge after you run the knife thru like they recommend or you will be sorry while running for the bandaids.
Answer: In my experience, I haven't noticed any scratches on the surface but it probably depends on how clean the sharpener is kept and maybe how rough the handling.  As the knife is drawn through the sharpener, the faces of the knife will rub against some plastic pieces (guides); maybe if there is some build-up there then it's possible.  Mine is still new so there's no build-up on the plastic (I'm guessing that build-up might happen, I don't know, I think I read it in the manual ... just only sharpen clean knives, I guess).Based on what the sharpened edge looks like, the sharpening parts (wheels?) themselves only contact the blade maybe 1/16th of an inch (-ish), at an angle, so they shouldn't touch the other areas of the knife.The only damage I've done to a knife so far was from lingering when introducing the knife into the coarse sharpening wheels.  A small divet.  Probably because of the amount of time it took me to think "oh, I see, that's what sharpening sounds like ..." and then "... I should probably keep the knife moving."  ... and, later, "oops.  ...at least I didn't start with my really good knife..."   That's the only knife with a divet, so far.