When the hair dryer is on, our 15AMP circuit breaker has been tripping
lately to the bathroom's outlet. Sometimes my wife sees a tiny flash
when the power to the outlet goes out. I just looked at the outlet
and it's a 20amp GFCI on the 15AMP circuit breaker. I just looked at
the three neutral wires on the other side of the pigtail and they are
melted.

So, here are a copy of questions

1. Should I replace the outlet with a 15AMP GFIC instead of the 20AMP?
2. Can I just cut back the wires that are melted and put in a new
pigtail or should the wires coming into the outlet box be inspected or
possible replaced?