Yes the axle pin presses out and the bearing and two shims can be removed. Make sure when installing the new bearing that the two shims are positioned on either side of the bearing.
I would recommend disconnecting the lead nut after installing the new bearing and checking to see how freely the carriage moves on the rail. You should be able to move the carriage by pushing on the far end of the gantry tube. If not, your bearings are likely too tight.
When I get a chance I will post a detailed preloading procedure.