Service Tip: After Rebuilding your 400 Vise Cylinder there will be air trapped internally. This air will cause drifting and fluid a bounce that will disrupt the proper operation of the Vise Clamp Pressure Switch. To solve this problem fully clamp and unclamp the vise (without material in the clamp area) as many times as it takes to alleviate the vise drift. Simply release the clamp button when the vise is moving, it drifts after release, you still have air in the cylinder.