Hi Ian,
As suggested there by photon when you go from the 'course' adjustment to the fine adjustment there can be a bit of a kick back. I have just got used to this.
As to the controls being stiff as suggested by woof woof, they can be adjusted to whatever amount of tension is required.
There should be no play in the head at all.
When in position it would be very hard to accidentally knock the adjusters unless they are set too sloppy.
Regards
Chris