I have a UCD 46 with a Saito 82 on it. I am trying to break the motor in and I am getting a very bad vibration only at certain mid range RPM's. I am running a 14x4 APC prop. The vibration was bad enough to strip out the canopy screws and break off one of the cowl bolt on blocks. There is no abnormal vibration at full power. The motor is brand new. Anyone ever see anything like this before?