Popular consensus is that while the Ender 3 is a great printer, the plastic extruder guide is a distinct weak point. The plastic part can be sawed away at by the PLA filament in just a matter of months. I’ve only had mine since December, and this is what it looks like:

So I did some research and found a quality but inexpensive metal replacement. It didn’t take me long to replace it; most of the time was spent because I had lost the hex wrench that fit one particular screw and ended up having to use my bike wrench. The new one looks good, and seems to be helping with the print quality.