sludge in the system. He could pay to have someone pump it down and then replace the refrigerant and that might help, but the truth is that these days mfgs are cheaping out on the capacitors. Which is crazy cause capacitors are pretty cheap.
Hard start kits used to be standard...until they weren't. Anything to save a few bucks. Locked Rotor Amps (the LRA rating which should be on the nameplate) are often well above the breaker size. The inrush current required to start a compressor can start to approach the LRA rating as it ages, which will start tripping the breaker. A hard start kit, which is nothing more than a secondary capacitor, can supply those extra amps needed on startup.