Just as an update to this, I serviced my turbine at the weekend, I managed to pick up a bargain on ebay for the 3 tonne hand winch £104 including the wire rope. Wrench cost me about 25 quid so already a saving on what my installer wanted and I'll have them for future years.

It was well worth doing as there was quite a build up on the slip rings and once they were cleaned I noticed a substantial increase in volts coming through, before hand I hadn't seen any more than 200 but as soon as it went back up it was pulling 250 and then yesterday 300.
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CJL