Freezer appears to be working, but not the refrigerator section - at most that will only get to 50 degrees. Manually switching to propane makes no difference.

the ptc overload on the compressor is defective,replace this and it will again cool properly

Sounds like maybe your element for Heating when on hydro may be faulty. A voltage check at spades on board connected to element will confirm. If power to element but no heat felt at element should confirm it's faulty. Remember, if stack is already hot from propane, element will also feel hot, so it has to be out or fridge cooled down at back first.(off)

You have a defrost problem. Remove the cover in the freezer and see if coil is blocked with ice.
If it is defrost it with a hair drier, check heater, timer, defrost thermostat.

Freezer fan not working or blocked by over ice formation behind the freezer. Switch of a/c for defrost. After some times, plug on . It's due to malfunction of defrost cycling. Keep thermostat at 5 degree and check thermostat, timer and defrost heater are working properly. thanks.

I believe it's showing the actual temperature that it's currently inside the refrigerator, not the temperature it's set at. At least that's how my sub zero works. You may need to clean the coils to get it to cool better.

I had this repaired by replacing the motor-fan in the refrigertor behind the air deflector which sends the air from the freezer to frig. hope this helps. The motor was not working.

u would need to replace heater and tstat and defrost timer depending on model

You're frozen up.  Defrost completely.  Then, clean your condenser.  Make sure to never leave open containers in the fridge...water condenses into ice.  If you still have problems, you may be low on gas.

We are not sure what precipitated the temperature swing up; however, within about an hour of emptying quite a lot of foodstuffs from top and bottom sections of the unit, I felt the cold air start to flow out of the rear vent. Within two hours, the upper section had dropped to about 50 degrees and by the next morning to 36. The freezer seemed to recoved on its own too, having risen to almost 8 degrees and then recovering to 0. Just patience and a smaller food payload?

I would look for a ventilation problem. If the fridge is working at that level nothing wrong with electric. The unit needs air to move up and out the top to make the freezer work. It sounds like the air is only moving the wrong way out the lower vent. Careful it could just be a birds nest but it may be a large wasp nest blocking the roof opening.