Geoff - the bed IS level in that picture.
Perhaps this helps - picture straightened out or at least as much as I can - software only let me move a degree of rotate at a time and it's between -1 and -2



Bed is parallel to the head. Its the bed carrier that isn't straight when the bed is.
Its the right hand arm is physically higher up than the left - so if I tighten up the left the bed would be at an angle