Backlash is the amount of free play between gears in a mechanical system. It can also refer to the amount of slop in a threaded joint. Backlash is most often caused by wear on the parts, but it can also be due to poor design or manufacture.
In many cases, backlash can be adjusted by simply tightening or loosening the relevant parts. However, if the backlash is too great, it may require more extensive work such as replacing worn parts or shimming components to achieve the proper clearance.
When adjusting backlash, it is important to make small changes and then test the system before making further adjustments. This will help ensure that you do not over-adjust and create new problems.