My MEC9000G is smoothe as silk FOR THE FIRST 50 +/- RELOADS. After that, there is a "hangup" or "bump" on the upstroke (only). There's never a problem on the downstroke, but about half-way up, it "bumps" or "bangs" and jars the entire reloader, getting progressively worse the more I load. I have cleaned the collett and lubricated the areas that the manual indicate need to be lubricated. The press is kept clean and covered when not in use and turns out good looking shells that perform very well. I just can't figure out what's causing it to hang up. Any thoughts? Thanks in advance.