Knocking noise momentarily in spin cycle cause?

I just bought a second hand whirlpool duet stackable washer wfw94heac0 is the model of the washer. The first time I ran a wash cycle I got this loud ticking/knocking noise during a brief moment on acceleration and a brief moment on slow down, about a minute total. From what I have read it sounds like maybe bad bearings but I have no idea. It only does it at certain points in the spin. Never when spinning slow or never at full speed. I took off the back and the noise is clearly coming from dead center underneath the motor and what I think says rotor assembly. Can anyone confirm that's a bearing issue? Or any idea as to what else it possibly could be? Again we just got it and transported it. I totally forgot about the 4 bolts and never put them in. Also it slipped out of my dad's hand when lifting and fell a foot or 2 (so that's great!) It spins fine but I've hit a dead end and really don't want to take any more apart if I don't have to. So far I have the back, top, and motor removed.