mimmo,
I've attached a couple of output graphs taken from the shop manual. The earlier generators should put out about 8A at 2000rpm.
Resistances are measured at 20degC (68degF) and are 0.145 (+/- 0.01) ohms for the armature and 8 (+0.1, -0.3) ohms for the field winding. This applies to both the 180W and the later 230W generators.
The manual gives the following trouble shooting guide for a system where the warning light does not go out even at high rpm:
1) broken connection between terminal 67 of generator and terminal 67 of regulator
2) oxidised or dirty regulator contacts
3) internal regulator contacts broken
4) broken or grounded field winding
5) broken or grounded armature winding
6) worn brushes
7) dirty commutator
If the warning light does go out but only at high rpm, the following:
1) short circuited field windings
2) field winding grounded to frame
3) large number of armature windings shorted
If this is the case then the problem needs to remedied as soon as possible or the voltage regulator may be damaged by the abnormally high excitation current that results from the low field winding resistance.
The manual also gives advice where the warning light glows feebly at highish rpm. In this case it is the bulb that is a fault - it is glowing at too low a voltage.
Some of this sounds bad, but I'm sure you'll get it sorted.
Hope all this helps,
Chris