Jogging your printer means that you are moving the carriage and bed along their given axis. When printing it is always best to make sure that your gears and axis are properly calibrated and sliding smoothly. This means that you should periodically check and confirm where “home” is for your printer. This can save a major headache when you prevent a long print from failing 20 hours in.
No matter the style of printer, each FDM machine will need to find “home” before each print. This refers to hitting an end stop in order to know where to begin. Since this is a mechanical process, it is always good to both visually and physically check to see if the X,Y, and Z axis are starting correctly. It is also very important to make sure you have a Level Build Plate and properly check the Z-Height (as mentioned later in this series)
If you are printing frequently you will want to make sure to occasionally lubricate the rods. When jogging your carriage or build plate you will often be able to tell if there are any rough areas that are not moving smoothly. You can do this with your hands when your stepper motors are turned off. If there are any areas that you can tell is not sliding right, add some white lithium grease or similar lubrication product.
Each axis in a cartesian printer requires its own stepper motor. This motor can wear out over time just like any other part on your printer. Screws may become loose and the pulley may not spin the proper amount of times in what the printer thinks is a full rotation. This will not only lead to XY Axis Shifts, as mentioned later, but it may make the print too long or too short in one direction, along with the under/over extrusion issues that come along with that. Periodically check your stepper motors and their pulleys to see that everything is jogging smoothly.