The answer to your questions is yes and yes. You can take a pattern off one of the good wheels and make a spring for that main wheel. Do you have a mainspring winder? If not you will have to pull it by hand, clean it, oil it and replace it by hand. You have to be careful that you don’t cone the spring to much. If you have a mainspring winder you can make a arbor to fit the mainspring. I use a Ollie Baker mainspring winder. I would then remove the springs with the winder and remove the arbor then do the next spring.