Outdoor Power Equipment and Small Engines - Snow thrower spring

I have a Craftsman 9hp snow thrower(model#536.887990), last year I replaced the belts and it still would not move. I had a pro come in to replace the friction wheel, he replaced the wheel, but guess what the problem was not the friction wheel it was the Traction Drive Spring. I ordered the spring from the manual that was shown, as it turns out, the spring in the manual is the not the one that is actually on the machine. The one that is on the machine is about 3/4 of inch long with 5 inches being thin like a wire with a hook, the hook connects to the Traction Drive Idler Pulley, the reason that I see for the 5 inches being thin and unspring like is so that it can pass between thr frame and belts without touching anything. The spring that is shown and was sent to me by Sears is all spring and actually will touch the belt when installed. This model is from 2002, I ordered the manual in 2005, (could not find the original) I think Sears revised the machine and moved the belts a 1/4 inch out so that a regular spring would fit. My question is where does one get a specialized spring.
Thanks
Gregory

What was the part number on the spring you got? The Sears site shows part#165X112MA and from the parts veiw it takes 3 of these springs. #234 in pic.
http://i369.photobucket.com/albums/oo138/indypower/B0211005-00005.png

No, part #234 is an extension spring, I ordered part #107+145, but neither one fit, there is no room for the spring thickness, between the belt and the frame.
Greg