Archer,
DE will often slump off and fall to the bottom when new, and the filter is reopened... At least it has in my case..
How are you adding the new DE? The best way is to put it in a five gallon bucket and then add water to the bucket. I am always amazed how much water will still fit in the bucket. Stir into a really thin pancake batter and slowly pour into the skimmer, with the pump running..
I suspect the band was not tight or the O-Ring pinched.
How far was the bolt sticking through the nut? I always whack the band with a rubber mallet as I am tightening it, even though I think they say not to do that..
You really have little choice but to re-lube the O-Ring and give it another try.
Thanks,
Jim R.