Old post I know but just wanted to comment. He says that the lines keep loosing slack. Try putting a couple of small washers on the inboard side of the engine causing it to point to the outside of the circle. This will help to keep the lines tight.

I have a Skyray also. Built recently ready for paint. Going to attempt to show my Nephew how to fly. I have had success in the past showing people by having them join me in the circle once the plane is up. Get behind them and slowly transfer the handle from my hand into theirs. No crashes and lots of smiles!

Wonder if Grant gave up??