Hi.
Check the defrost system. If the evaporator coils are icing up because of a defrost system malfunction, then the condenser will go under stress, and the motor will run most of the time. A test on the defrost system can be done by performing a complete defrost manually (remove food and leave power disconnected overnight). If the fridge restarts working after defrost, then problem was the defrost system. In that case the problem may return after few days or weeks, meaning that one part in the defrost system is faulty.Parts such as defrost thermostat, heater, fan and defrost control must be tested.
If the defrost makes no change, the refrigerant gas pressure may be insufficient, and for that reason the compressor is running most of the time. In that case you will need to call a technician to check gas pressure and eventually to do a recharge.
If finally the motor is humming and clicking most of the time, but not properly starting, then the problem is usually the starter relay/capacitor. Relay and capacitors can be replaced to fix the problem.
Here all parts and diagrams for this unit:
TPX21PRBBWWRegards.
Ginko