You said this was a 77 dist? Just checking, but was there one or two VR pickups in there? I know some of the Z dists had 2.
Have you checked your pots, I believe it's R56 and R52? Don't quote me on those numbers as I haven't messed with my MS in a while. Although if Matt will humor me and send a kit to an APO address I could tinker with one in Iraq...lol
Anyhow, check the two VR pots and make sure they are turned completely counter clockwise until the click. It seems the VR pickups are very weak and MS has a hard time if the pots aren't completely open.