Wheel cap for Scott's fertilizer spreader

We have a Scotts Turf Builder EdgeGuard Mini Broadcast Spreader for spreading fertilizer and weed killer on our lawn. The problem is that lots of the early season weed and feed type fertilizer is supposed to be spread when the weeds are wet, to ensure that the granules stick to the leaver and they get treated and killed.
The problem is that the wheels on the spreader are open on the inside. So, they get wet too and the spreader is throwing out fertilizer. This gets gunked up inside the wheel and then periodically is heavy enough to fall out of the wheel in a big clump. This is usually too much fertilizer and kills a spot in the lawn.
This is just a simple little cap on the inside of the wheel to keep the moisture and fertilizer granules from being able to get inside the hollow wheel.

I had to print on a bigger printer than my Prusa or Ender (I have an ArtistD Pro that I hate for everything except larger stuff). I think the wheels have changed a bit over the years, so you may just need to break off the hooks that I included for my wheel design. I have found it still works great even if the hooks aren't engaged well.