It's a push and turn thing. You have to press on a pair of latches on either side of the yoke cover while rotating it on the shaft cover. Once released, the yoke cover should slide down over the shaft cover.
My finish mower came w/ a Eurocardan shaft and getting the cover off the first time was terrible. Mine had a white stiff plastic piece which held the U joint 'cuff' to the shaft cover. The first time off one of those busted. After getting it apart I ground the pawls which held it in down a bit. I do agree that this design isn't the easiest to maintain.