OK. I put a multimeter on the batteries and they were all reading around 12.6volts. I removed the battery adaptor and connected a large floor battery (charged up to 13.5volts) to the camera. The camera sometimes manages to reach 75fps, but only just, and the rest of the time it fluctuates between 50 and 60fps. It's almost like there isn't constant power reaching the motor. Wiggling the power cable near the connector doesn't make a difference, so it's probably not due to a bad connection. I've sent CE an email with the serial number to see if they have any suggestions. I have a battery discharger which I always use to keep the batteries in good condition.