Go to Butkus and dl the manuals, is you mount this on a #2XXXXX series FM and have the ring around the shutter release turned the wrong way it will give you grief.
Thanks y'all. I figured out what I was doing wrong.... all three times.
There are a lot of things that you have to have in the right place, and if any of them are out of place, it wont work properly.
I didn't realize that I needed to leave the advancing lever pushed in, while the meter worked off the drive. I figured I needed the lever out to run the meter, but after reading the manual that wasn't correct.
It seems that I have a perfectly good, and properly working MD12 now.