i will say from my experience with cracked things - it all depends on the crack/metal, its a long time before you realize they are cracked, sometimes there is even rust internally on things before they fatigue enough to finally break, im glad this broke right away because chances are if it had not i might have had to pay for it later not knowing and just suspecting the cause - no one is perfect - my cousin has a 1206 Farmall, was hauling hay with it like he had done a hundered times before FOR YEARS, had just rand down the road hi speed turned into our old home place was going slow up the driveway and snap, rear axle broke, right inside the rear housing, rear wheel bent the fender in and pinned him in the seat and broke a couple ribs, the shaft looked like it has been cracked for years and finally came in two, it was rusty inside from moisture over the years before it finally broke - who knows how long it has been - that tractor has been ran hard for years, running duals, disking etc......i dont expect everyone and everything to be perfect and catch things 100% of the time, I know the mechanic and svc mgr well enough i feel comfortable in knowing they did their best. I never pressure them with a time frame I just let them work.
