It might be a little small to spot any build-up of dirt, even with a light. Do you have a wooden toothpick or something like it that will not scratch the metal? It is the sides of the port you want to try and scrape clean, so not all the way in the back.
Maybe you can find some better tips online for cleaning, but it seems like this is the problem you are having since it just stopped working suddenly without updating or changing any settings.