Well I found the problem. At first I was ecstatic. I dropped the tank part way, and was able to extract the sending unit.......................
Upon complete removal of the sending unit, I noticed it looked pretty rusty. Then I tried to move the float arm...it had some resistance. THEN the really bad stuff happened--I made the mistake of looking at the internals. Apparently the car must have sat for a VERY long time without much gas in it, because the entire sending unit is rusted up good. Peering into the internals, I noticed something that gave me pause--the electrical pickup the float arm is supposed to move against seemed a bit out of place. Closer inspection revealed it wasn't attached at all, and a slight shaking produced a most disheartening result--it simply fell out in two pieces..............