In comparison to the size and strength of the arm (which you...

In comparison to the size and strength of the arm (which you acknowledge is 'massive') a brick is small and weighs relatively little. There is very little stress placed on the arm.

Moving parts can be lubricated to reduce wear and tear. Parts can be replaced over time.

If you were correct and this was such an obvious problem, this is something Caterpillar would have picked up before entering into the MOU. It would not have taken several months to figure it out.

I suppose this is why you start your post with 'My guess'. These forums would be more useful if there was less guessing and more informed or substantiated opinion.