Euro Reef - RS model

It could be a cold solder joint very common in solder joints that were soldered VAI wave soldering or a person with a shaky hand. It can also be in the plug-in head if the wire has broken it will heat up and the insulation will exspand and break the conection I've seen this a few times. This is why you are suppose to unplug electrical items by the plug-in head.

Bill