My tow car has a 13 pin euro socket. My caravan which doesn't, is connected with an adaptor. This has been working ok till recently but now the connections are hit and miss. I've checked the original caravan plugs and they are ok but if I waggle the 13 pin plug while its in the socket the connection makes and breaks. I'd like to inspect the electrical connections inside the plug but cannot see any way of opening it. Can anyone tell me how do I do take the plug apart?