I have a Dillon super 1050 with which I've loaded 140,000 rounds plus of 45acp in the last 3 to 4 years. In the last six months the powder measure started to dump Clays very inconsistently, which it didn't prior to that time. Anywhere from 4 or 5 round per hundred would be undercharged with powder so that firing the round wouldn't fully cycle the slide and the bullet impact at 50 yards was about a foot too low. Around the same time, the operating handle stopped returning to the full upright position, but was ignored as I figured what difference does that make? A few weeks ago, the handle completely jammed when one broken end of the tool head return spring telescoped inside the other, jamming it in the spring tube. After a certain amount of flailing around the problem was spotted and the spring replaced, thankfully a spare was handy.
Now the handle stays up by itself, and the magically the powder measure problem with clays went away. Not sure why this happens, but if you powder measure becomes suddenly inconsistent, you might want to check the tool head return spring.