whirlpool washer topload gearbox?

[Jimholms]

Top loader.  Confirmed motor coupler is broken.  I've got the motor off and the gears should be free.    The agitator will not turn manually (with the motor/coupler disconnected.)  Does this mean it needs a new gearbox?  The tub will turn by hand.
Jim

Model gst9875jq0

[AJ]

The agitator will not turn manually (with the motor/coupler disconnected.)  Does this mean it needs a new gearbox?

No it does mean that it needs a new gearbox.

If I wanted to test the gearbox I would remove it from the washer first.
Then I would turn it by hand the same place the motor coupler would turn it on the short side shaft.

I would turn it one direction to see if the shaft agitates back and forth.
Then I would turn it the other direction to see if the clutch spins.

But before I did any of that if it had a broken couple I would slap a new motor coupler on there and give it a try. 99% of the time when I find the motor coupler broken all I need to do is replace the motor coupler.