Be sure to check each of the grids thoroughly. I've had several (Hayward Pro-Grid) come un-stitched at the bottom end.
If you have the grid assembly apart, look down the tube (from the top) of each grid for cracks and breaks.
Breaks will be obvious when looking through the hole, and the broken plastic can cut through the fabric.

But I think Manslick is right, sounds like too much DE