Remember also to only use it outdoors or in a well ventilated area. If lever A becomes hard to push, chances are the gear ratio is wrong. Use a wrench to adjust the coil length while ensuring the synchronistation wheel is set to P if this is the case.
The 'butterfly effect' may also occur if button 'S' is 'pulled' rather than 'pushed'... try holding your grommets together for a few seconds to minimise this...
Or get yourself a Trustan 40(a)... much more reliable...
zac... it is false economy buying the '40' model... as the '40(a)' has hit the market at the same price... and has the upgraded 'bumphukkit' bracket - which allows for maximum pressure without foregoing flexibilty...