If the compressor is hot to touch this is usually down to a system fault. This is usually down to either a faulty compressor or a gas problem.
Now for this you need to get a fridge engineer in but due to the age and the cost of the repair its proberly not worth it as a new compressor fitted is about
£200+ so its probberly not worth it on this its better to just replace the freezer rather then fix it as once you break into the fridge system its more prone to faults in the future.
So sorry its not good news but if you need anymore info just get back to me.