Is there something in your mode of usage that is causing this to happen? Usually, the power cord is a snug fit in the socket, and will come apart (disconnect) if moved with slight axial tension.
If this were mine, I would place the power supply connector end in a bench vise jaws and slightly make it out-of-round. By doing so, I will increase the retaining force of the connection. Have a micrometer handy for measuring the out-of-round condition. Start with 0.002" difference.