I have to admit that I have to stop and ponder the same thing when I replace the bolt in that arm that breaks. I want to say that it hooks on the bracket that is above. Post what you find !

I think it does attach to the bracket. It seems to be working fine now.

I took some photos quite a while back to answer this question before. I couldn't find the old post, but here is a link to photos from my L111 that might help clarify how the spring was originally installed.
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Below is the link to the original post I was searching for if you are interested...

http://forums2.gardenweb.com/forums/load/tractor/msg0615121716989.html