It is also an improvement occurred, the zoom drive Geling considerably "smoother" and less choppy. Still not perfect and really not good enough! The lever of the Foton FRG 13 can indeed be screwed firmly but not rigidly connected to the ring so he only slightly bends before passing the motion of the lens. Furthermore, for my purposes would be a bit of a lever makes sense (even better: two different), so I can not even move the lens ring.
The Foton FRG 13 can be readily fixed to the lens and then keeps reliable. To summarize: it is an improvement, but not a breakthrough to solve my "Ruckelproblems".