In the older Maytag transmissions, the only thing I recall failing was the small gear which is made of nylon. The teeth would get worn down and it would slip during agitation. That old style has to be removed from the washer to make repairs though.
"Lead, follow or get out of the way." Larry Adamski
On my old Maytags (MAT 21s, if I remember correctly) the transmissions had bushings instead of bearings. The bushings would get worn and allow water to seep into the trans. past the seals. This would take out the pinion gear. I tried replacing just the pinions, but with the worn bushings eventually the water would fill up the trans. and then the oil/water mix would get into the wash tub and spot customers clothes. I think the only way to rebuild them correctly is to replace bushings and all seals along with the pinion. To replace the bushings they have to be pressed into place and then reamed to fit the shaft. Typically a job for a machine shop. I saw an advertisement once for someone offering rebuilt trans. for around $70, but I replaced all my Maytags at about that same time and never tried them.