I recently removed the 44" mower deck, on my 2012 Simplicity Regent tractor, to sharpen the blades. I then replaced the deck and cut the lawn. The next week I noticed the attached spring, lying on the deck, under the belts:
I scoured manuals and parts lists, but cannot find this part anywhere in the diagrams of my mower deck. It's clearly not the big spring for the belt tension, and it's not the spring for the hitch (both are still there).
I think that's probably it, though it's tough to tell from the diagram where, exactly, the spring goes. I'll take the mower deck off and see if I can find out.
Results Information including wiring diagrams. Without removing deck, check front hitch & see if spring is missing, located in illustrated parts list pages 70 & 71 item 11. Springs hooks from raised tab in hitch to center of rod item 2.