Kenmore dishwasher - low pressure to upper rack

Hello,

After getting poor cleaning of the top-rack items, I've determined I am getting poor water pressure to the top rack. I've placed a cereal bowl above the inlet in the top rack to catch whatever water comes through and after 10 seconds it is barely half-filled.

I've checked the trap and it's now clean, but the problem persists, while the bottom rack consistently cleans well. Would this indicate a failed circulation pump or could the line to the top rack be blocked? If the latter, do you have any suggestions to check or clean that line?

Thanks