Sears 110.26912691 Washer - Fills / Agitates / drains but will not spin.

My washer of about 8 years will fill, agitate (although it sounds rough) and will drain but it will not spin. I have looked though all the advice online and I took the unit apart, removed the pump and motor and it appears (except for some wear) that the coupler is intact and not broken. Although I can not verify that since its apart. I took the agitator off to look for loose clothing or somthing stuck found nothing. I did not take the "c" clamp off the agitator not sure what else to do to check. Should the "drum" spin freely because mine does not. Should I take the "drum" out? If I do what am I looking for. What else should I try? can anyone help?