Came out to perform preventative maintenance on package unit. Inspected filter, coil, blower assembly, motor, capacitor, heating elements and other electrical components. Heating elements have are starting to slightly droop in some areas. Made customer aware that this is a sign that they are starting to wear out. Checked operation, amps, and temperatures. System is still operating properly. Discussed with customer about previous issue with air flow and how to address the other side of home having air issues now. Advised customer that when it comes time to replace the package unit, that the ductwork can be more easily accessed at the unit. We can enlarge the intake and the output duct sizes to increase air flow to help balance it out.