I found a couple of interesting things. First off, I noticed that I still had powder clinging to the metal base of the powder dispenser and I was still getting measurements right around 4.5 gr (after cycling through all four stations). I also noticed that leakage was still occurring between the bottom of the hopper and the auto-disk. While having the cavity over of the whole, where the powder falls into the casing, I scraped the leakage off of the the auto-disk into the hole so that it fell into the casing and then took the measurement. I noticed that the weight increased some but not enough to approach 4.8gr.
I decided to empty all of the powder out of the hopper and take it apart. I sprayed a bunch of powder graphite on the metal base and brushed it around with a vinyl brush. I made sure I put a bunch down the tube, covered the ends, and shook it back and forth to get a nice coating on the entire surface. I shook off the excess graphite and scraped off any residual that was still in the tube. I screwed the hopper back on and filled it with powder.
I took several readings the were consistent with the earlier measurements I made so I decided to increase the index of the auto-disk from .40 to .43. After cycling through all four stations once, I went through all four stations a second time and then measured the amount of powder dispensed. It was 4.8gr on the head! PROGRESS, finally!!!!! I took 10 measurements that averaged out at 4.74gr with a low of 4.5gr and high of 4.8gr.
There is still some leakage occurring between the hopper and the auto-disk but not as much as before. I also did not observe any powder on the metal base of the dispenser through ten measurements.
So there looks like there were several problems at play. The first was that I was still experiencing some static buildup on the powder dispensing mechanism, I was missing the O-ring between the top of the riser and the powder dispensing mechanism, and the .40 cavity was just not dispensing enough powder. I also think that the more I work the press the more it's going to "break in" and settle down.
Thanks to everyone for all of your advise, especially CaptainXL and dfk. I feel encouraged after making some progress and I'm closer to getting this press dialed in. I still plan to take a class. I found a good instructor through the NRA web site. He's a little pricey but he only teaches two students at a time out of a shop in his house and he's been doing it for 40 years. Looking forward to having some fun, finally!!!