when I did mine I had trouble with no power and hard starting. I then messed with the fuel screw and it went better. I didn't do anything to the IM spring, just the main spring was shimmed about 1/4" maybe a little more. But if you noticed when you put the top of the pump on there the holes had a little room so the top can move. I think this makes the shaft, idle, and main screws off from where they were before. I just did the trial and error until it was good.