Student or Learner
"Sometimes, when the plug is inserted into the socket, there is no resulting supply of electricity to the plug. When that happens, withdrawing the plug and re-inserting it properly fixes the problem. The problem appears to be caused by a failure to insert the plug properly. How would you describe this?"
I would say that the socket has "an intermittent" or "a recurring" problem.
I'm not a teacher of English, but I have spoken it for (almost) all of my life....