What exactly does F 21 flashing on washer mean??

F-21 means that it's taking too long to drain. This could be a broken pump or some stuff in the pump or drain hoses. I had this problem last week and I fixed it myself with a pair of pliers and torque and phillips head screwdrivers.

If there is water coming out of the drain hose when it's running, then the pump is working. (The drain hose is the thing that comes off the back left corner and runs to an inlet against your wall.)

Unplug the machine and turn off, then detach, the hot and cold water hoses.

To clean the pump and drain hoses, you will need to take the back and top off. Very easy, just lots of unscrewing with the torque screwdriver. Have a little bowl handy for the screws. Then tip the machine forward, lid side down.

If the drain hoses are translucent, as mine are, you can see if they have gack in them. Unclamp them with the pliers. (Squeeze the things together and slide the clamp back up the hose it's holding on.) I had lots of gack (we're dairy farmers) and cleaned them with an unbent coat hanger with a piece of rag crimped on one end (use the pliers). There is a hose outside the machine and another one inside the machine. I also cleaned the elbow between them.

The two things inside the machine that you should clean are the rubber funnel that first takes water out of the drum (mine was black) and the pump it attaches to. These hose clamps were especially easy to unclamp. Take the funnel to the sink and wash it with hot water. The pump attaches to the bottom of the washer with red rubber seats. They are very easy to detach. Then you can take the light-tan pump on the left off the motor with the Philips screwdriver. Take the pump to the sink and clean it out. Mine had nails, a battery, money, a pencil and some other stuff. Remove any stuff and clean out both sides with hot water.

Then put everything back together.

This whole project should take an hour, maybe two. The Sears repair guy sucks and you don't need him.

Check the drain line for kinks or obstructions. Check the pump. Remove the hoses from the pump and use a flashlight to look into the suction port. Look for anything clogging the pump (like the occasional stray sock) and check the pump impeller. Make sure there are no broken/missing blades and that the impeller will spin freely. If any blades are broken/missing or if you cannot get the impeller to spin freely, the pump is defective. Hopefully it's just a clogged pump, drain line, or a jammed impeller.