OK, I'm stumped.

My 79 300SD won't start in the morning. I have...

-5 working pencil-style glow plugs (all tested at between 0.5-0.7 ohms resistance)
-A good strong battery (tested at Les Schwab, confirmed to be good)
-A working alternator (also tested at LS, with an output of 15V!)
-A block heater that comes on 3 hours before I have to leave in the morning.
-New pre and primary fuel filters.

I've tried running the GP's longer, I've tried charging the battery overnight, tried running the block heater ALL night, and even with all that, I barely get a crank at all (turns VERRRY slowly, like the battery is dead... but it isn't).

I ONLY thing I have yet to do (waiting for the wrenches to come in the mail) is adjust the valves (no idea when they were last adjusted, only acquired the car about a month ago). Seafoam does nothing to help.

So, if the valve adjustment does nothing (which at the rate things are going, may be the case), then what could be the problem? Any ideas? Help!