Removed the plastic agitator. The coupling was stuck inside the top of the agitator. There were 3 small slots in the top of the agitator. I was able to stick in a small skinny shaft screwdriver in a tap with a rubber mallet in a circle pattern. After about 15 minutes of banging quite hard the coupling cam out.
(By the way no instructions came with the part---WH1X1944) The hard part was getting the coupling to line up with the groves in the agitator & every time I tried it got stuck in the top of the agitator. A repeat of the tapping with screwdriver and mallet over & over again for about 10 times. Finally got it lined up and then had to struggle to get the agitator on completely. On the last 3" to 4" had to use the rubber mallet and small block of 2 x 4 and tap hard on the block to get it into final position. The washing machine is working fine now--probably saved over $350.