I remember going through the same thing on one of my cars. The earlier production tii masters from Ate used the smaller grommet. The later production ones switched to the larger grommet. The good news is that with the larger grommet it's easier to punch in the new plastic elbows. Lube with a little brake fluid and punch them in after the rubber grommet is in the master. Those elbows do get brittle over time. Also, the blue braided brake fluid hose can be hard to get on the elbow too. Hose on elbow first with brake fluid lube. Then punch into master. The black colored brake fluid hose from BMW is easier to get on than the blue kind in my experience. Works the same just doesn't look as cool. I've broken new plastic elbows trying to get the blue hose onto the elbow before, black brake fluid hose (BMW) much easier. My .02,
John