Whirlpool LA9500XTWO direct-drive washer agitates fine for a bit and then goes clickety-click [video]
And Master Nickfixit nails it:
recheck the motor harness connections, make sure the harness is fully seated. Some machines had an extra 2 wire harness connection that can work loose, these were 3 speed motors.
Source: Whirlpool washer LA9500XTWO slow agitator and grinding sound