I have never been successful with top feeding and don't even care anymore. Feeding a 3/0 spiral blade down through a hole drilled with a #70 bit,,, means your are going against the teeth which makes it very easy to bend the blade.
I have said this before, but I find for bottom feeding grinding the top of the blade to a sharp point really helps also. I have a grinder near my saw and it takes a second or two to do. I do it on all my blades.