What's the number from below the seat?

TIA Tom. The number is 71428

I did get through to Toro with that number. The spring is called the deck engagement spring but their diagram doesn't show where the other end of the spring attaches to and this is what I need to know.

On the XL style decks I can think of 2 springs. One that is attached to the end of the cable that goes to the deck idler arm. There is also a return spring that pulls the opposite direction on the arm and hooks on a kind of s hook that hooks through a hole near the left rear of the top of the deck. Sometimes those drop away. Yours may be new enough to have an eyebolt rather than the s hook. In either case an s hook or eye bolt from the hardware store will work- possibly needing a spring extension depending on what version you have.

Thank you Tom a very clear explanation. I did actually find the eye bolt on my own after jacking the tractor up and crawling underneath on my back. For some reason I was looking for a place on the chassis but once I thought about it there was that eye bolt starring me in the face. Thanks again.