Simple, just stretch the spring you have. It won't take much to fix it right up. It's the one under the plunger cap under the front of the trigger on top of the trigger guard.
If you still want to get a new spring, just call TC with the part number and they will sell you one. Just don't tell them what you are up to, just ask for the part.
If you are still having trouble, E-mail me and I will cut you a new spring from some spring stock I have. It would cost you a buck including postage and the envelope.
I'm sure just stretching the spring will work great for you.
Good luck.
Joe
jcunclejoe@aol.com