I am new to clipless and had the same issue with the yellow tabs breaking off. Probably from walking or putting the cleat down when not stopped. But the first one fell off within a week. I quickly came to the conclusion that if they fall off that easily I'll just live without them. As best I can see, the only function of the pads is to prevent wear on the more critical parts, when walking. I have a couple thousand miles on my cleats sans yellow pads, and function is still fine. I inspect for wear to the critical surfaces from time to time. Yes, Shimano says replace the cleat when the yellow pad wears away - but i f the darn things fall off in the first 100 miles or so, I'm not going to rely on that to tell me when to replace them.
Just my $0.02.