12 years old - When it stops running hit makes this one loud thud sound? When we opened the back we found a steel rod lodged under the fan and the motor was very hot. Once we removed the rod the sound stopped to return later but much softer. What else could possibly be causing this sound?

It could be very dirty. I have seen that cause it to be noisy. Here is a manual: https://dl.dropboxusercontent.com/u/8010163/GE_Profile_Artica.pdf
What was this steel rod?