I have a kenmore 665 dishwasher where the spary arms do not spin.

Pre-wash may be compromised and a new power circuit board may be needed.
My advice: As long as the other cycles are accurate and work as usual; Pre-wash in your sink (spray off waste material) before you place the dishes in the washer and commence cleaning. Its best to wash off food and other material before washing in the machine to avoid clogging the drains and pump.

How old is the dish washer?

timer is sticking or bad replace the timer

You may have a bad pump, or the pump intake (inside the bottom tray, under the dish racks) may be clogged with crud from years of dirty dishes.

Power off, check for clogs and if water supply to arm ok. Remove any build ups and reconnect. Good Luck.

you have a bad water valve or bad user interface that's the long control in the front of the dish washer.

You need to check the arm's holes for clogs. If the water is filling and draining well, the only water that circulates is being pushed up through the center hole or tower.

The angles of the holes cause them to be little jets when the water rushes out. No water getting through = no jet = no spin.

wash them by hand

could be faulty outlet pump

In my case, I had the same problem until I realized the drain hose was not looped high enough. Once I looped the drain hose higher than the dishwasher, the problem went away and it washes dishes perfectly.

When the drain hose is installed too low, the water in the machine will only stay as high as the hose is installed because of the laws of physics.

The same applies to laundry machines - that is why the drain hose is set to drain from a higher point than the drum of the washer.

Good luck and Blessings!