1 You can get to the yellow knob and selectors working from inside and lifting the floor out. No excuses....
2 The yellow knob relseases a spring loaded pin that releases a spring loaded selector shaft so when the bits get dry or dirty they stick. Pulling the red lever into low and back into high latches the springs.
3 Get a garden sprayer and fill with dilute PVA then spray the asbestos cement sheet all over, that seals the dust, then take iff and put it in bin bags and seal them. Wear disposable overalls and a hat (mutton cloth works) then fold it all into the last bin bag. I wear old clothes and bin those too as you don't want fibres in the washing machine. The sealed bags are OK to go to the local dump as asbestos cement is approved for land fill (it where it goes anyway). HSE have a whole suite of guides aon how to do it.
http://www.hse.gov.uk/pubns/guidance/a14.pdf
Its one of these jobs wher a few hours and a bit of thought will save you £1000s and if you follow the guidance you will do it as well as the professionals.