There are other telltale signs that your freezer isn't functioning properly, such as the following:
Excessive frost build-up in the freezer
Freezer is no longer freezing, causing all the ice to melt and leak
Overheating compressor
Persistent loud motor sounds from the evaporator fan
Freezer burn on the containers and food
Make sure to watch out for these signs so you can start working on the DIY fixes. More importantly, you know when to schedule a service call when the problem becomes more severe and persistent.