The numbers you gave are missing one very important piece of information, what was indoor wet bulb temp? with that you could determine what the target S/H should be.
I agree that it probably is a little low on charge, if nothing has been done to it in the nine years I would first check that Coil is clean, blower wheel is clean and then recharge unit, probably a piston metering system so S/H is the important number.
Good luck and glad to see you are getting to work on a unit, be careful and do not hurt yourself.
Mainstream Engineering Certified.
HVAC/R PM Technician.
410A, & GREEN HVAC/R Technician.
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