Originally Posted by Hissing Cobra
BTC, the purpose of the 3rd hole closer is to reduce the amount of fertilizer that is coming out of the spreader when the deflector shield is in the "down" position. When it's in the "down" position the fertilizer that is normally thrown out the right side of the spreader is now being "re-directed" to the front and left side of the spreader, making those areas "heavy" with too much fertilizer. Early in the season this will result in deep, rich green coloring on the edges but if done during the summer heat, it will cause those edges to burn out. Closing the 3rd hole when the deflector is "down" allows for the front and the left side to continue getting the correct amount of fertilizer and you won't have those issues.
Ah. That it would be a nice feature. Ask me how I know. Unfortunately, I was spreading one of Lesco's products that contained Lockup. My lawn has mostly recovered. Having grown up on a farm, and spending lots of my time applying fertilizer and herbicides, I felt pretty stupid for not adjusting the rate accordingly around the perimeter of my yard.
Considering it's purpose, I wonder why they discontinued it.