Hello. I purchase a jeep compass limited 4x4 2009 model in 2012. It had been used for just 1 year and parked for about 6 months before I purchased. It had done7 miles at time of purchase. Currently, I have done 6k miles. I loved the car until mid this year. I began experiencing some heavy movement under the car and was told by mechanic it was the differential. We got it changed, now the car can barely run beyond 80mph and the transmission is terrible. The car fails to change gear quickly with the accelerator pedal on the floor, picks up speed very slowly. There is also this revolving sound beneath the car when when I am about to take off. Sounds like brokenballs in bearings. Is it possible to get assistance in this forum. I love this car to bits and not thinking of selling it off anytime soon.