Agitator only turns clockwise (Whirlpool top load)

If you said washer spins and drains fine meaning the clutch is fine, too. It seems you have the transmission bad.

You have bad agitator dogs . Easily replaceable and inexpensive . Remove the center bolt holding the agitator on and seperate the 2 agitator pieces . You will see 4 teardrop looking pieces ( dogs ) . Replace and your done .

you need to see if the motor turns one direction during wash and the other during the spin. If so, your gearbox is faulty and needs replacement. If motor only goes in one direction at all times, then very possible, the timer is faulty.

there should be 2 or 3 springs that hold it, they mite have broke, take off back panel an check.

Assuming that this is a basic Whirlpool top load, direct drive, neutral drain washer, the agitator is supposed to stop during the spin cycle.

Please see the following Whirlpool installation and service manual for top load machines.

If you look at the description of how the transmission works, there is an "Agitate Cam" that lifts the "Agitate Gear" out of contact with the main "Agitate Rack" when the machine goes into spin mode

https://secured.whirlpool.com/Service/SrvTechAdm.nsf/2cd44500d572193285256a45004fd9d6/f7e2147fa98b28cf85257122007475cb/$FILE/L-55.pdf

I have found though that because of the friction between the agitate gear and main drive shaft, including the oil itself, the agitator may move while in spin mode.

Sounds like a burning out motor to me...

The ***** part of the agitator is supposed to ratchet in the clockwise direction. this is normal. If you can spin it in either direction (turned off) then you need a set of agitator dogs.

if its a 2 piece agitator.. the gears in top of agitator is stripped out.. change gears be like new....spin top countor clockwise if it dont grap.. gears bad

sounds like the spline is stripped on the agitator take the bolt out of the center of the agitator remove the agitator and visually inspect the splines let me know if this works

The inside tub moves on the spin stage only and cause the water, by a centrifugal force, to be forced out of the clothes. During the wash cycle,the tub is stationary and the agitator moves forth and back. If you would like to remove the agitator - Remove the inner agitator cap (inside the top of the agitator) and then open the screw (be aware not to lose parts !) Good luck !