My model MAV6451AWW washer will not drain. If I manually move the dial (to the area on the dial for spin), it will start draining during a spin cycle.

Does washer fill, wash and drain? This washer is a straight forward unit and that complicated like new front loads. If unit fills, wash and drain, then I would lean toward a timer issue. With the unit filling, washing and draining, that tells me lid switch is good, motor runs in wash direction, pressure switch is working and tub is not locked down. Also, if motor turns one way, then motor is good. If unit is not doing the three things, then could be lid switch, pressure switch or bad motor.

Possible there is problem with the timer controller unit. It seems that the stepper motor is not moving to the next cycle until you manually move it to the spin. You can use some contact cleaners on the switch and also carefully try to see if the timer moves within , replacement is a costly issue and must be debated

bad control board

Check door switch: If the lid switch is bad it will not drain or spin. Try this test: With lid open let it finish wash cycle. Press lid switch down with screwdriver. Washer should begin draining. Release switch. Motor should stop. Press switch a second time. Washer should start spinning as it continues to drain. If motor doesn't come on while lid switch is pressed, replace the switch. OR
http://www.youtube.com/watch?v=q942xn_2VXY

If you can manually advance it and it works then yes the timer will be the cause of the issue.

Bad timer. Try to find a used one if possible, this item is a little expensive.

the timer may need to be replaced.. it might not be clicking on the spin cycle. try moving the dial manually to the spin mode.

door switch bad?

where is the lint trap located

Check out your outlet filter, probable it is clogged. Clean this out and refit. Most cases when the drain or spin does not work, it is the filter. This is a suggestion.