How to Fix Frigidaire UltraQuiet III (FDB750RCB0)?

The lower rotating arm rotates normally, however the upper arm does not. During observation of the hose leading to the top arm, water can be seen moving up the hose, however as it gets to the top there is not enough water pressure to fill the hose going over the top of the unit therefore, only a trickle of water flows into the upper arm assembly. All filters have been cleaned. Could it be the circulation motor?