I would guess that the suspension would be the main culprit here. The Mega track suspension, if travelling slowly, unlocked and in "active" mode, can set up a type of oscillation effect. Traveling on uneven ground, it will adjust, making the whole crane tilt just a little, with that huge boom in the air, a little movement on the axles, makes a lot of movement up there. Then the suspension gets pushed on the opposite side and pushes back. Back and forth, side to side it can set up a rocking motion, and then "dink". I'm sure the book says travel this way only on a "smooth, level surface, at only creep speed, suspension locked". Real world conditions seldom are that way. Typically you manually level the crane, lock the suspension, drive slowly till the slope gets too much, unlock the suspension, relevel, relock, and continue. Leaving the outriggers out and "skimming" the ground is a great security measure. If it started to go, they would catch it, and if even hit hard enough to bend those, they are just quick detach on them, and much cheaper/easier to replace than a boom and damaged carrier. Keep it safe everyone.