Some chambers have to be maintained more than others for sure. The majority of the people have the most maintenance after the warranty period. The cheaper chambers with mostly plastic instead of steel components and lower gauge thickness chambers usually are the ones that have the window leaks and zipper problems. Remember that this doesn't usually happen after about 2 years. I have not seen any chambers fail within the first year so.
Some of the compressors have better filters and some zippers need to be lubricated more than others. Some hyperbaric chambers are harder to clean than others also. If the home is dusty you might have to clean the filters twice a month under the bathtub faucet rather than once a month.
The biggest maintenance concern for most is the fear that the zipper will get stuck while in the chamber if it is not oiled regularly. Some people over oil their zippers in fear that they will be stuck in their, mostly the claustrophobic people. It is called zipprephobia, the fear of having your zipper stuck at the worst possible time. I have a whole page on zipper concerns as it has recently become an issue among those that are cannot afford the oil less zipper chambers.
Another maintenance issue is window leakage. This does not mean you have to spend 500 dollars to fix it as it can be repaired/refurbished. The problem is the shipping. The shipping back and forth and having to wait to get your chamber back. Some manufacturers will send replacements to use if you have that condition in your warranty. This is why buying a new one has all these bonuses. If within 2 years, you have a problem, they will fix it and if a manufacturer defect or problem not from "misuse", they usually cover shipping back and forth. Just check this before you buy. I have reviewed warranties and every hyperbaric chamber company has different viewpoints of misuse, etc. The last person ozonated their chamber to get rid of the off gassing smell and their chamber turned yellow. All they had to do is wait a few weeks. This was before people could request a chamber that has been off-gassed naturally. Certified used chambers almost always are off-gassed depending on how long they were used. Many people put their chamber in the sun to off-gas their chamber.
As far as maintenance, knowing the usage of the chamber is usually the best way to know how it will hold up. If in a high traffic clinic, some types of zippers hold up better but for residential, not everyone needs the best zipper. All zippers are FDA cleared for safety. This is not a safety issue. It will start leaking and the chamber won't inflate when zippers fail. Or when a window leaks, it won't go up to 1.3 ATA pressure. Everyone is worried about a chamber blowing up if a window fails or the zipper breaks. If the chamber is maintained and used as they say "under normal usage" the chambers usually don't need to be serviced unless it's time to be serviced years down the road when the manufacturer has told me their chambers should last for.