Transfer Case problems of the 2011 Lincoln MKX

Have owned this 2011 Lincoln Mkx awd approximately one year. During that time I recall about 4 times during this period, when going from a coasting down the hill mode on surface streets, to placing foot gently on gas pedal as leveling out and or starting up a slight incline, a loud, jerking slam has been heard and felt. Enough each time that I thought I had been rammed from behind by another car only to find there was no car behind me. The car would then continue on as if nothing had happened. The most recent time I encountered the "slam" was the evening of wednedday 4/24/19. This was the same situation as previously noted, when going from a coasting mode to driving with foot lightly on accelerator, a loud slamming noise was heard and felt. Last Friday, 4/26/2019 when driving on a 35 mph zone, it sounded as if something had gotten stuck under the car, sounding like a dragging branch, or a dragging brake caliper. We checked under the car and looked at brakes. Backed car up and heard a faint metal sound, then drove forward and heard the dragging sound again. Rather than risk driving the car further, had it towed to the dealership where it was diagnosed with a a problem with the power take off/transfer case. It will have to be repaired/replaced as a high cost.