Just bought a new C3410 brush cutter. Noticed a hard vibration at full throttle. I put my tach on it and it revs to 10K rpm at half throttle then dies off from there. When the throttle lever is fully squeezed it drops to around 6k rpm and vibrates hard. Runs really nice at half throttle. I looked in the book and all it lists is throttle lever free play. There looks to be no carb adjustments or throttle lever adjustments. Anyone have any ideas? It is brand new so under warranty, but I bought it online and I have a feeling a local dealer may not want to bother looking at it. Thanks.