Kitchenaid washer with very slow agitation

My washer was only agitating ccw. I replaced the dogs and the coupler. Now the machine will agitate both directions, but the agitation is slow when the machine is unloaded and gets weaker when clothes/water are added to the basket. When I removed the cabinet to replace the coupler, I did notice black rubber shavings on top of the gearcase. Gearcase was replaced under warranty in 2009. I’m not sure where to look next.

If the base of the agitator agitates slow, you may have stripped agitator splines, just pull the agitator and check.

I’ve pulled the lower agitator and the splines are fine. Agitator shaft moves very slowly as well.

jumped the lid switch and the checked the motor. it runs fine.
Clutch is spinning fine during spin cycle.

I wouldn’t think the gearcase would be bad after 18 months but I could be wrong. Could it be anything else?

I would pull the tranny, put the agitator back on and turn the coupler counterclockwise. Agitator should go back and forth, if not, new tranny time. To confirm, you should feel something irregular while turning the coupler.