This was a filter I got for free with purchase of a tank also has a super slow out putas an FYI EVERY time you clean your canisters you should lube your O-rings.
Once a month I pull my impeller out and clean the chamber. I have an old school rena xp4 which is a good filter for the most part. I have the lid off anyways so why not just clean it.
If this is your first canister you should check it once a month to gage how long it can go without cleaning (depends on your stock) it's all a reference point and no one can tell you exactly when to clean your filters do your best to figure it out. Check your input and output for cracks order a new seal kit regardless and like tomojsg said ad silicone if you find a crack just keep the media and sponges wet in a 5 gallon pail while you wait the 24 hours for the silicone to dry