Recently my MBP developed a weird, very intermittent issue. When i plug in the power cord into the laptop, the green light illuminates very dim instead of usual bright green, and the laptop shows that it is plugged in but not charging. It usually starts charging after i plug it in and out a few times. Is this a known issue or my power supply or motherboard going bad?' I already cleaned the contacts, so it is probably not dirt clogging up the connector. I am a bit apprehensive about taking it to Apple, because it is such an intermittent but annoying problem which is rather difficult to replicate.