That SOTA Reflex clamp is a good one. The collet chuck, in the centre, is adjustable. There is a hex screw that you access from the bottom, which allows you to drop the chuck, a bit, so that it sits flush, when clamped. Unless the spindle is tapered early, or the chuck jaws badly worn, you should be able to adjust the clamp so that it gets good purchase, with the right amount of clamping pressure. If the jaws are worn, I would call SOTA to see if replacements are available. I have the I-clamp, and I love it.