Secondary Drive Shaft
Also there seems to be on-going issues surrounding the fracture/failure of the secondary drive shaft, leading to the scenario 13snoopy detailed. And whether to use the Rotorway smooth belts or Pro-Drive toothed ones. It's a shame because it's a very pretty aircraft and I, for sure, would consider one if it weren't for these issues.
But then you have to decide, do you buy a kit and build it yourself (and how much confidence do you have in your own ability) or do you buy a used one and put your life in the hands of someone else's building ability. It's definitely an aircraft for an engineer.