Ok, stand down on this. Seems like the problem is electrical. Noticed the insulation on the wires both inside and outside of the mechbox are chewed up at several spots. I fixed one of the bad spots and it now fires, although heated up enough to melt a wire on my battery (no fuse). I have all the wiring from a TM mechbox that I'll transplant tomorrow.
At least now I know I'm not totally lame and I did the shimming correctly.
