What are you using to measure the capacitor?
If using an Ohmmeter it only measures resistance not capacitance.
Make sure the light goes off. I had on the switch was bad and with the
inside light on it wouldn't get down to temperature.
Also check fan(s) if it has them on the outside on the coils or
compressor and inside in the freezer.
Could be the self defrost heaters are staying on all the time or justto
long.possible cause as someone else mentioned the thermostat or timer.