Hi Rory, just reading up on your build to get some ideas for mine (which even start until after xmas at this rate) and its good stuff.

For your linac problems - I'm not sure I understand the whole situation but, and shoot me down if I've got the wrong stick here, could you not employ a simple lever mechanism on the flipper/lift to give the desired speed/strength ratio instead of mesing with different gears motor side? It's a lot easier and cheaper to make some levers and pivots than it is to change gearbox ratios.