Follow-focus pushes lens up/down slightly

I recently bought a Filmcity camera rig and a nice two-stop FC follow-focus to go with it..using them with a Canon DSLR camera. On trying out the follow-focus I'm noticing that as I begin to turn it one way or the other, the camera lens will kick up or down ever so slightly as the torque from the follow-focus begins to transfer motion to the gear ring on the lens. Once it's turning then things seem to settle back as normal, and if I verrrry slowly start the movement then it seems to be minimized or not occur.

I've tried using a Canon 55-250 lens as well as the basic 18-55 short lens, tightening the camera down as firmly as possible, and still it seems the follow-focus wants to raise or dip the lens a tiny bit as it starts to adjust the focus. The problem may not be a game stopper, but obviously it means that when filming you're going to see the image rise or dip slightly when you start to turn the follow-focus...which is frustrating.

My guess is that the width of the DSLR camera, held by the single 1/4" screw, just doesn't give enough base area to hold the camera firmly on the rig, but there must be some way to deal with this.

Anyone seen this before and know of a solution to it?
 
Filmcity/Proaim is not exactly known as the pinnacle of quality. Cheap rigs are cheap and that’s the first problem.

Anyway, you might have your FF butted up too tight against the lens gear. The FF should be close enough to grab hold of the lens gear without slipping, but no so tight that the torque moves the whole camera.

If you do that and you find there’s too much play in your FF, try opening up the gear box and packing it with grease. So much grease that a little bit oozes out when you close it back up (just wipe off the excess really well). That’ll create some pressure + lubrication that minimizes slipping of the internal gears.
 
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