This is a repost for Gerry, Rachel and others as the original appeared
truncated....
One way that I've tested the generator to see if it is functioning at all
(w/o removal) is to polarize it with the appropriate battery (6V with a 
6V generator, 12V with a 12V generator).  This is done by removing the 
fan belt such that the generator/fan assembly can rotate freely.  Connect the
wire from the D+ (armature) connector on the generator to the positive post
of your battery. Connect the terminal DF (dynamo field) to the negative
post  of the battery.  If there is a third wire/terminal (D-) this should also
be connected to the neg post of the battery.  This will cause the generator to
behave as a motor and will become properly polarized.  BTW, when I removed the
generator for replacement/repair removed the carb., and intake manifold inorder
to get the generator separated from the fan housing.  My fan housing could not
be lifted up (no room).
christian