I have four new 24 teeth gear wheels cracked. Only one of them was in use for several hours inside steering mechanism with a very low stress, and the other three gears were not used before, they cracked while building, when I put it on the axle. I wrote to the Lego company about broken pieces, so I am waiting for a response.
I don't understand why it happened Also I have several old 24 teeth gears, and they are ok, they are much stronger and they don't have any cracks, but the new ones (bought in 2015: 42009 set and 8293 set) all cracked(