Frigidaire dishwasher upper arm not spinning

The upper arm on our 11 year old Frigidaire dishwasher won’t spin. The arm can be spun manually and the holes appear to be clear. I ran it with the door open and it looks like a lot of water is flowing thru it. All I can think of is that either the tube going up to the arm is restricted or the pump is going bad. I hate guessing when the pump motor is $150.00.
Any ideas?
Thanks
Tim