When the stem cracks, it does so at the point above the E-clip, so the stem ends up falling through the sleeve. The die will not work with a cracked stem.
I did the same, moved to Forster or Wilson inline seaters... I don't do compressed loads anymore, but the forster seaters are just as good as the redding and cost less... The Wilson's are my favorite seaters, a bit slower but not much and it doesn't bother me to load on them.
`It's your neck tension and the clean necks causing your problems. I have the same probelm and this is how I fix it. Load all bullets .015 longer than the desired depth. Pile them up after you seat the bullets. Then take each one out of the pile and measure the depth, mine vary out to around .005. Group them in small piles based on that measurement you get. Adjust the die for each pile seperately and they will all be the same depth when you are done. Also shoot them in groups based on the piles they were in, this gets you shootin all similar neck tension bullets together and you will get allot less flyers.
I should have worded it that it sometimes does so above the E-clip. At least, that is what happened to me. I haven't seen a cracked stem lengthwise, but I guess it does happen.
That is your problem, SS cleaned brass removes all the carbon inside the neck, carbon inside the neck acts as a lube or a barrier between the copper and brass, if you continue to SS clean your brass lube the inside of your necks with a dry lube, Imperial has a kit, I bet your required force to seat pills decreases and much improved consistency in Ojive length.