Pat,
If you look real close you will probably see the broken end of a little brass lever that turns this light on and off.  The lever gets bent when passengers get in and out of the van.  After a few bends and a few straightenings (is that a word) the lever breaks off.  I always look for spares for this light when I find a Vanagon in a wreckers yard.
George
'85 Westfalia