The answer to 'how to maintain vacuum' is to regularly clean and maintain your vacuum cleaner to keep it running at peak performance. This includes emptying the dust canister or replacing the vacuum bag, cleaning the filters, and checking for any clogs or blockages in the hose or attachments.
It's recommended to empty the dust canister or replace the vacuum bag after each use, and clean the filters every 3-6 months depending on usage. Check the manufacturer's instructions for specific cleaning and maintenance recommendations for your vacuum model. If you notice a significant drop in suction power or the vacuum is not picking up dirt and debris effectively, it may be time to have it serviced by a professional.