When the solenoid on my starter went on my defender it sounded much like the problems you described. The price of a starter her in OZ was quoted at around 1300Au inc fitting. When asked if the solenoid could be fixed the dealer said that it was sealed unit. Before forking out the money I removed the old starter and found that the solenoid could be opened, with encouragement. what I found was that the small copper plate on one side of the solenoid was worn (from high curent) on the oposite side the matching coper plate was fine. After a quick trip to the auto electricians and 2 dollars later a replacement part was found. 3 hours work 2 dollars and a few beers later all is back to normal.
Adam
