Generator Problem

Is the output overcurrent protection device correctly set and in good order?

It may be a brushless design, so the diode and resistor, or thyristor, on the armature may be dead.

Alternately the capacitor has degraded. This fairly common.

This as well as - not instead of all else above.

But I'd start at the capacitor - it's a cheap item and no pull down is involved - if that's all it is.

If the unit was not used for over 6 years (?) then:

After checking all that MoronicBumble (#1) has suggested and found every thing OK (or not sure...) do the following:

1) identify the Field connections. They are normally marked X and XX or + & -

2) Check that they are coming from the Voltage regulator if there is one (electronic board) or it could be a simple transformer + rectifier diodes. This type of transformer system is called a compound system... Anyway, disconnect the two wires from the rectifier or voltage regulator and connect them to a battery (12V or 6V DC). Just For A Short time like 3seconds. You can do this several times at intervals of ~ 10 sec. (2 or 3 times). make sure you are connecting the field winding and not the voltage regulator.

Explanation: These generators rely on the remanent magnetism in the iron of the rotor. If for any reason this magnetism has gone, due to not being used or sometimes due to a heavy short / overload of the genset, there will be no generation of any voltage.

The short application of a DC current on the field coils will re-juvenate this magnetism and allow the unit to build up the required voltage on starting.

Try the unit and see if it starts to generate a voltage.

If not, you have a bigger problem and as #1 answered ....

Probably the remenant magnetism in the core is lost. Do "field-falshing" (i.e.) apply 24V Dc to the field terminals for a very brief period. The voltage would build up fast and the magnetism in the core would also build up.