The spray bar doesn't turn.

Clean the spray arm

If the spray arm doesn't spin, remove the spray arm and clean it.

First take out the wire baskets by removing either a cap or pin at the end of the sliding tracks. Don't fret about a little water on the bottom of the tub. It's supposed to be there. It keeps the seals in the pump and in the motor assembly damp. If they dry out, they'll crack and leak.

The spray arm cap twists off with a clockwise turn, just the opposite of a regular screw. Twist ties, rubber bands and plastic and paper often show up in the spray arm. You might have to use a needle-nose pliers to pick them out. The pump usually sucks up most of this stuff, but if you hear a sudden loud grinding sound while running the dishwasher, something like broken glass might be stuck in the pump intake. Unscrew and remove the pump cover to check it out.