Dust boot won't return or go down (air cylinder)

The air cylinder air adjustment screws need to be open so that air can properly get to the cylinder. The jam nut keeps it in place and sometimes the jam nut comes loose and the adjustment screw backs out or screws in too far and cuts off air.

You don't want it screwed in all the way, as this will stop the air flow:

There should be 2 in total on each side of the spindle. Make sure they are not screwed in all the way. This will return air flow to the cylinders and allow the dust boot to move up and down freely.