The tickovet seemed a little erratic so after some looking through the notes of the v8 register it seems that the stepper motor could well be the most likely cause.
I was surprised at the cost of these but after putting the part no into ebay I found some at less than £15 …. they are the same as used on the Landrover and Rangerover cars.
When it arrived it was quite a simple job to replace it.
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