Can't get screw loose on Kenmore dishwasher(665.1559579)impeller.

Check the shaft of the impeller, the plastic shaft might be broken, it was the problem with mine. To get to the impeller you have to remove the filter at the base of the diswasher and after you will see the screw that hold the impeller assembly in place, unscrew it and you will see right away if it is broken, Good luck

Hello,
This means that some debris is trapped inside the motor. You can complete this repair yourself, it's simple. Remove the lower spray arm followed by the screws on the top of the motor housing.
The impeller will be below the part that lifts off with the screws removed.
Appliance & Refrigerator Parts

you can acess the impeller, by removing the lower spray arm, ther are 5 torx scrws holding the motor cover down, then from ther ther are 2 additional torx 15 screws covering the pump outlet and impeller housing, the impeller is spring loaded in place.

You can lift off the wash arm and pump screen. You will see the pump shell with screws to separate the top from the bottom. Next is the wash impeller with a center screw and a drive washer. Under the impeller are shims. Don't loose any. The same with under the drain impeller. Just be methodical with your disassembly, lay the parts out in a row as you remove them, and reassemble in reverse order once you have cleared the problem.

remove the D/W from power
remove the front bottom grille
reaching under the machine with a flashlight ;you will see a black rubber plug held on the pump bottom by a spring clamp remove the clamp with a spring clamp plier put your index finger in the pump and, carefully attempt to turn the pump impeller until it spins (the debris that was holding it will fall out
put everything back and, repower the machine

The impeller get new and change it
Vitally

The pump may have something lodged in the impeller and will not allow it to pump. To access the pump, the drawer must be removed and turned 90 degrees to the left. Unplug the wire harness to the pump. Loosen the clamp on the drain hose and then remove 3 screws holding the pump. I've found rubber bands wrapped around the impeller.

not overfill since no water overtop just switch detecting too much water...lean washer back remove 3 screws holding bottom panel on newer pumps have torx screws in bottom id any way possible remove a much water as possible first may try leaning washer foward after removing bottom panel remove the screws in bottom of pump and clean..older pumps were harder to clean and replacement was easier but more expensive..new style comes with motor attached

The leak is coming from the main seal? The chopper thingy on these old machines will not come out without a fight. These impellers have been there a long time and has had lots of hard water and crud to hold them on. Get a screwdriver or a reasonable facsimile and carefully bust it off. Be careful not to damage the shaft. If you pull the whole motor assembly out, replace the rubber gasket too.

I checked. There is no sheet of any kind inside or below the door of my Whirlpool dishwasher.

In any case, opening up the non-washing washer revealed that the filter behind the chopper assembly was clogged with food. I cleaned it off, put the thing back together again, and it was washing dishes again, until about three days later. I took it apart again and found food clogging the filter behind the chopper. I thought the chopper wasn't chopping, so I replaced it. It was around $16. About three days later it wasn't washing dishes again.

Further examination (dis-assembly of the sump motor and impeller) revealed that the end of the impeller (which is designed to engage the chopper) had broken off, thus the chopper no longer spins with the sump motor. The impeller costs about $20 and isn't too hard to replace, as long and you keep track of what you've dis-assembled and put it back together in reverse order.

On whirlpool dishwashers, the sump motor drives the impeller (it's connected via the threaded end of the motor shaft) and the impeller, in turn, drives the chopper. The chopper you can replace from inside the tub, without removing the dishwasher from its home or taking apart the sump assembly. But save your $16, as that probably isn't what is wrong... The impeller, being screwed onto the motor shaft, requires complete removal of the dishwasher so that you can completely remove the base assembly that holds the motor assembly.

If you have a GU-series whirlpool washer, the tech manual can be found here:

https://secured.whirlpool.com/Service/SrvTechAdm.nsf/2cd44500d572193285256a45004fd9d6/52521bdbd0ef763c85256cbc00520548/$FILE/8178022.pdf

It has complete instructions for the replacement of every part.