Washer Agitator not moving

Working on a Maytag Washer Model LA506 Series 10 Serial # 200331XN. This unit has the orbital transmission not the flat or helical transmission. The washer fills and then advances to the wash cycle. Soon after entering the wash cycle a burning smell is noticed (I presume the belt is slipping and getting hot). I place the washer in the spin cycle to empty the tub; the washer tub spins and the water does empty properly.
Further examination shows the agitator is jammed somehow, it will not move in either direction. What steps can I take to find the faulty component?
Thank you for your assistance.