GSF would be the cheaper option for new but you could always have yours rebuilt
by a good Auto Electrician.
If the Bearings are ok then its most likely that the Brush Pack on the rear has
worn out.
Its the black plastic round faced bit with a metal backing plate thats held in place
by 2 screws.
Undo the screws and remove the Pack and you will see 2 Carbon graphite Brushes.
Measure the free length of the brushes themselves and not the metal casing they
protrude from
Minimum brush length is 5mm so if you have more than that (10 or 15mm) clear
of their metal holders then something else is to blame.
Try starting the engine and using a voltmeter (multimeter) set at 20volts DC
touch the probes of the meter on the battery connections and you should
get 12 to 13 volts but sometimes nearer to 14 volts.
Get someone to raise the engine speed slightly above tickover and have them
switch on the heated rear window + the heater and lights.
The meter should still read 12 to 13 volts.
If it doesn`t then you have either worn brushes, weak brush springs, a faulty
voltage regulator or diode or at worse, the winding of the main shaft has rotted
causing a phase shift in wich case it`s fooked.
This can also be that where the brushes rub on the spinning shaft, it may be
badly worn to the point of shorting the windings.
You can buy/order the Brush pack through any auto electricians.
The Part number is on the brush pack itself.
Hope this Helps.
Regards, Fred.
