I actually never tighten my vice all the way so the grip can move on purpose so I can adjust needle depth quickly without having to buy adjustable cart grips or constantly tighten and loosen my vice. If you don't want it moving and your vice isn't clamping tight enough put a layer or two or masking tape around the part of the tube that goes into the vice for a quick fix. Being all Bishop stuff you're using one would think the vice would clamp tight enough. Not sure what style vice they use on that machine but maybe take it apart and look for some burrs or something that inspection might have missed. Co worker of mine just recently got an Edge X and the give wasn't working. Took it apart and there was a small plastic shaving in there that was messing it up.