patchy or no deposition

[dead_plaines]

I am plating machine parts for a bridgeport mill, such as dials, knurled lock rings, handles etc. I am very careful and follow the directions to a "T". The first thing plated was a handle. It was polished to a high luster beforehand and the results were good. I plan on buffing the part again as there seems to be a fine roughness to the surface.
My real question regards plating parts that were sand blasted, and not polished. I successfully plated one dial and achieved the look I was after, which was kind of a Butler nickel, but a little shinier. In all subsequent tries the parts are incompletely plated. I have attached several pictures to help illustrate my problem. A an example, the plating will be everywhere except one small place on the outside of the dial. Or on some areas but not others (see pics). High areas and low areas appear the same. It seems to match the "gray color" complaint found elsewhere on the forum, but there is no plating underneath to buff, just bare gray or brownish metal. It's not burnt as described in the troubleshooting guide, there is no crusting or black streaks so I've dismissed over amperage. The parts were originally black oxided, but that was worn away years ago. So the presence of "zinc" has also been dismissed. The copper wire that holds the parts plates great, but not the part. It can't be a brightener problem because I'm not even getting a plate let alone one that's hazy.
Now after reading the forums, I am getting conflicting information: Is the formula 1 amp per 16 square inches or 32 square inches? Should the temperature be maintained at 70 degrees or 110 degrees? 5 minutes in the degreaser or 1/2 hour?
I would also recommend posting pictures of problems, errors and bad plating examples. I already know what a successful job it should look like, that isn't the problem, so viewing and studying all the success stories doesn't help me solve my problem.
Thanks,
dead_plaines