I submit that the lift arm cross brackets broke because the lift mechanism was overtraveled: It tried to raise it higher that the cross piece had allowance for. It hit the bottom of the frame bracket and that eventually cracked the metal. This situation is probably caused by the lift mechanism being out of adjustment (too much vertical travel), or the front mower hanger is in the wrong position for the given tractor mounting brackets and tire size and type. I know that guys like the mower deck to be as high as possible for ground clearance and they want it tight against the frame so it doesn't wiggle around. But, I say its been lifted too tight against the stops. My Deere MMM could also be put into this situation but there is plenty of adjustment room.
I'll bet there is a recommended MMM elevation guideline mentioned in the manual.
I'll bet there is a recommended MMM elevation guideline mentioned in the manual.