Originally Posted by Hissing Cobra
Your 50 pound spreader will have the 3rd hole closer on it as they all come from the factory with them. Look on the front of the spreader just above the impellar on the right hand side. You should see a stainless steel thingy hanging down. Simply push it toward the back of the spreader and that 3rd hole will close. Pull it back out and it will be open.
I'll check it out and report back. I'm curious now. If it's there, I'm guessing I will realize that I have seen it before.