When my Frigidaire dishwasher (Model FDB636) has gone through all of
the cycles and shuts off, the dishes are not clean and the detergent
is only damp.

I've turned the control knob through each of the cycles. The motor
runs through the various cycles but, in the "fill" cycles, I can
barely hear water entering the tub. (During the "drain" cycles, any
water in the tub is being pumped out).

During the "fill" cycles, when I open the door, I notice water just
trickling into the tub through an opening on the left wall of the tub
(above the Overfill Protector).

Shouldn't that flow be stronger so the water would dissolve the
detergent and get pumped throught the spray arms onto the dishes?

P.S.: The owner's manual shows a "nozzle and upper spray" on the top
of the tub. Should water be pumping through that nozzle, too?