[Sam Mac]

I see a couple things that bother me.
1: It looks like the arm that the pulley bolts to is bent slightly upwards

2: If it was my mower I would shorten the tube that the pivot bolt fits through about 1 coil of the spring and shim it at the top the amount that you cut off so that it can't just move up on the bolt. You should be able to find some machine shims at TSC.

3: Your missing a grease fitting in the pivot bolt. Item#21 that should be pressed into #22

Edit: One other possibility is they gave you the wrong spring, if you look at the wear marks it looks like it should have one more coil and that would bring it up higher.