Mario- ok ill try to make it more stable
David- I made the gearboxes myself- gears from technobots then bought a couple of plates of aluminium and drilled some holes using a mill with digital read-out

Also, here is a video of the flipper in action and self righting. Unfortunately at the end one of the elbows snapped which meant all the gas went out! Then a deans connector worked loose so it stopped entirely but that's not in the video.