Actually, there are two springs, and there both present. I was just trying to determine if there was a way to adjust the rpm's manually, I guess there isn't...
I have a toro super recycler walk behind that will not run at the proper rpm's . If I rig the idler arm , I can ballpark it around 3000. There is no tension on the idler arm spring and it then runs too high. Something else must not be right because the spring does not control the rpm's by...