Here's what's wrong with your frigidaire dishwasher-
the check ball/diverter to top spray arms is an example of poor engineering.

if you replace EVERY single part inside your dishwasher, motor, control board, etc, that nylon ball check valve might operate properly 10% of the time. The real problem is not with the pump or the ball itself or the switches, or ANY of that. The problem is with the microcontroller (the computer) running the program for the wash cycle. its not pausing the motor long enough for gravity to make the ball fall into the other position and block the lower arm ports and divert the water upstairs. thats how it works. a brief STOP of the motor causes gravity to make the ball drop back and the spray of water forces it to close off the ports to the bottom spray arm. then--- a longer pause causes the ball to fall all the way back to the place where it closes off the top spray arm. but after watching this thing run about 300 times, its obvious the program is just incorrect. and there is no feedback from the dishwasher motor assembly to the computer to tell it whether or not the close of this check valve successfully took place. so it runs thinking it is cleaning top rack, but it sure isnt.

the solution is to get frigidaire (electrolux, whatever) to admit this flaw and offer a replacement control board with corrected pause timing, but as far I know they have not. the same control board that has the bad program is still the only one they offer for this unit.

so take the lower spray arm out, clean it while you are at it, remove the 3 screws that hold in the venturi cover over the check ball.
take out the check ball. throw it away in the trash. some kid might choke on it. put it back together. now your dishwasher has one cycle called "ON", ... and both arms (all 3 in some models) will spin and clean dishes.

if your pump is clean and strong enough it should do just fine.

‘ItsAllBroke’: considering the likelihood of Frigidaire retroactively resolving a design issue on a 5 yr old dishwasher, pursuing other options seem more worthwhile.

Interesting idea you suggest. A couple gaps come to mind that I’m not able to bridge though..
(1) It worked great until a defined point in time several months ago, and has not worked successfully since. Not an occasional/periodical issue, and the design of it obviously didn’t change during that time. Doesn’t seem to fit the scenario your described (sometimes works, sometimes doesn’t).
(2) I would expect that the water pressure would be cut in half if the checkball were removed/discarded, which would seem to limit the ability of it to spray/clean effectively. Curious if this is a theory of yours or how many times you’ve successfully done this before. For perspective, would you be willing to briefly share the experience that this suggestion comes from?

Joe/APP Team – your thoughts/input on this theory?

Thanks for the ideas/suggestions!