Hummelbird Nose Wheel Steering

Hello everybody! Glad to find this forum. I've got a tri gear Hummelbird that was built by someone else out in Ohio. It came to me via Enid Oklahoma a couple of years ago. I'm in Minnesota. Anyway, the original builder made a fully castering nose wheel assembly, no connection to the rudder pedals at all. The castering nose wheel would get into a wobble from time to time, just like a castering grocery store cart wheel. The 4th time i flew the plane the metal that the nose wheel yoke was made of broke right next to the weld that attached the yoke to the front strut and the nose wheel flopped over on its side. Bad luck i guess, and bad judgement on my part for flying the plane knowing it had this problem. Anyway, i've converted it back to the original plans configuration where the nose strut is linked to the rudder pedals with several bits, including two springs referred to in the plans as 'cot springs', and that's what this post is about. If anyone has any familiarity with this set up i'd sure like to know what you used as 'cot springs'. I've tried three different sets of springs and am not at all sure i've got a suitable set of springs in there right now as i'm waiting for the weather to clear off enough to taxi test it. Tried to get the hangar door open yesterday, an actual above freezing day, but no luck, the door was frozen to the floor at the bottom edge seal. Any advice or info appreciated. Thanks! Bruce