I'm more used to working with larger scale industrial equipment where the user/operator can exchange parts and actually change lubricants etc.

As far as home/personal devices the best you can really do is clean out any filters, get rid of dust etc and listen for when the motor inevitably fails or starts to fail at some point.

Not sure why you are being downvoted. Most of those home dehumidifiers don't have any user serviceable parts outside of a paper filter. Even inspecting the components would require a laborious disassembly of the device the manufacturer never intended.

You're cleaning the filter. That's more than a lot of people do.