JD L100 series mower deck broke

[68GS400]

My 4 yr old JD Model LA115 mower deck broke. It broke where the blade spindle goes thru the deck. First the belt came off and when I went to reinstall I noticed a lot of movement in the spindle. I took off the deck and a piece of metal 1" x 1 1/ 2" fell out. I did not think it could be welded so bought new deck for $650.
Did this break because someone hit something, due to vibration is spindle was loose, or some other reason? Have any other forum users had this happen?

 

[RandyT]

The reasons for the deck cracking and breaking could be all the reasons that you mentioned.

 

[mfreund]

The L series are made to hit a price point requested by retailers. As a result, things that need to be built better are not. Four years is a long life for the L series. Hope you get another four years on that deck.