Alma

I didn't buy one, it is a bit out of my price range - but I made one almost exactly like it. And tried several variations of it. I found that it "moved" the wolf, but did not eliminate it. Did you find thew of is gone, or if you hunt around for it, can you still find it in between notes someplace?

It is possible mine did not work as well as the original, but it did seem to work exactly as he described. I found I could "tune" the C siring tone, which I liked a lot, but I could not do that without affecting the tone of the A string. 

So, I ended up with a bunch of magnetic on my white board  

I did find that "tuning" my after length seems to help more than anything, but if I searched long enough I would still find remnants of it in-between a pair of notes.

I am not saying it doesn't work - I was not able to give it a fair test, since I had to make one. I have read unpaid testimonials from people that I expect know a lot more than I did that swear by it, and say in decades of playing they have always just worked around that fingering. People that are leads in major orchestras. 

So, my guess is it was a combination of me being a noob, my cello was an "expensive" student cello ($5K) so not the best, and setup. If the cello I am making ends up with a wolf, I expect I am going to be very tempted to spend the $100 bucks or whatever it is to get one and try "the real thing"