Electrical Questions? Ask an Electrician Online.
Hi, I'm Mike G and I'll be assisting you. I suspect there is a loose connection on the receptacle. Open the box and check for either a loose screw termination or the terminations in a pushback. If a pushback, they always fail and the device will need to be wired to screw terminations.
Either the hot or the neutral is physicly breaking connection on the out going wires. You need to verify both. Are the wires terminated under screws or in pushbacks? If pushbacks, that is where the failure is.
Let me know how it goes.