I had that problem here with my first needle scaller, it lasted like 5 hrs.
But I bought it at Princess auto here in the Toronto area and there return policy is great.
They say you can bring back any tool anytime for any reason, so I did. The second one is a much better construction then the first.
Also I would only use it to take of the hard black under coating. I added some rubber foam to the handle and body to absorb the shock to my arms, it can cause nerve damage if you do it for a prolonged time repeatedly.
If I could have gotten it media blasted I certainly would have.