Machine is about 40 years old. It was turned off and allowed to defrost. Several days later it was turned on again. It seemed to run normally for about 20 seconds, then the compressor sound changed to a sort of hum, for 10 seconds, then the noise stopped After about 10 minutes the compressor started again and the sequence repeated. The compressor gets quite hot - nearly too hot to touch. The inside does not get cold.

Is this a common fault? Is it repairable?