If the X-axis or Z-axis travel seizes up while trying to move or while cutting a file, the bearing boxes may need to be flushed out and then greased. Inside the bearing boxes are bearings that move in a single-file fashion as the bearing box runs along the guide rails on the X-axis and the Z-axis. These bearings could dry out over time (if not maintained regularly) or there may be some debris (sawdust, etc.) that accumulates in the bearing box along the path that the bearings run, causing the bearings to catch and stutter, and ultimately causing the travel in that axis to seize up.
If after going through the deep cleaning steps - HD5xx Series Lubrication Guide - the travel is still seized up, the first thing to do would be to thoroughly wipe down the guide rails, removing any excess dirt, dust, and debris.
Power off the control box.
For the X-axis, back out the 5 bolts of the panel on the right side of the X-box (indicated by the yellow arrows in the pic below) using a pair of *needle-nosed pliers ( * for machines built before June 2021 ) and a T-27 Torx screwdriver (also shown below).
** The needle-nosed pliers would be used to grip the lock nuts on the inside walls of the X-box.
** Position of lock nuts on the inside of the X-box - 4 accessible from the front indicated by the green arrows in the pics below. 1 accessible from the (top) back indicated by the red arrow in the pic below.
Once the right side panel has been removed, the 2 X-axis bearing boxes should be visible (circled in yellow in the pic below).
Take the Dry Silicone spray DuPont Non-Stick Dry Film Lubricant and flood the guide rails right up against the bearing boxes. Now take both hands and move the X-box to the right as far as you can, and then move back to the left. This process will work the Dry Silicone lubricant into the bearings themselves, both flushing the debris out and temporarily lubricating them for smooth movement. Continue these steps (flooding and moving back and forth) until the X-axis moves freely.
** The steps to flood and flush the Z-axis bearing boxes would be the same as the X-axis steps. **
Once the bearing boxes have been flooded and flushed, take the grease gun and grease the bearing boxes.
Firmly place the tip of the grease gun extension on the top of the zerk fitting (indicated by the blue arrows in the pic below) and squeeze one full pull on the trigger. This will shoot the grease through the top of the zerk fitting and into the chamber that holds the bearings in the bearing box.
** There may be a little grease that accumulates around the tip of the grease gun extension - this is not an indication that the grease is not going into the bearing box.
Once the bearing boxes have been thoroughly flushed and then re-greased, power the control box back on and test the axis in question to verify that it will either move left to right and back again, or up and down without restriction.
Links to grease and other lubricants:
https://nextwavecnc.com/product/linear-bearing-grease-and-6mm-nozzle-kit/
https://nextwavecnc.com/product/linear-bearing-grease-refill/
https://nextwavecnc.com/product/dupont-silicone-spray/
https://nextwavecnc.com/product/crc-3-36-dry-film-lube/