The cartridge spring holds the case in position at Station 1, not just to help with case entry into the die, but to maintain alignment after resizing so the case lines up with the primer punch.
The top of shellplate to shellplate platform distance should be around 0.125", and this should be sufficient room for the cartridge spring. If the die is hitting it, the spring is in the wrong position.
It should be radially aligned with the shellplate center bolt, and lay nearly flat on the shellplate platform. As you insert a case, the spring should ride above the rim, and then snap back to just hold the case. If it is too far toward the center, it will interfere with indexing.
Fig. 16 in the manual shows a picture of this, but there doesn't seem to be much text to explain how to adjust it -
You will notice an adjustable retaining spring at Station One. This spring should be adjusted to almost contact the case when it’s placed in the shellplate.
I would imagine that this spring would have to be adjusted to handle widely different case diameters, just like the locator buttons have to be changed to match. (Unless you load a lot of calibers with the same diameter, like .30-06 Sprg, .243 Win. and .45 ACP. Then you can use the same locator buttons, shellplate, and cartridge spring adjustment...)
.30-06 Springfield: 100 yrs + and still going strong