Is anyone having a problem with the spring coming off of the Salad Chopper? I have had two do this. The first time it happened, I wasn't even using the chopper, but was holding it up to talk about it; when I opened it up and started showing how it worked, the spring popped off. I did an adjustment; sent that one back and received a new one. Last night I was using the new one for the first time to shred some chicken and about half way through, the spring popped off! Is it just me? Is there some kind of art to using the chopper that I am not aware of ?