As predicted, it was the resistor block at fault. I decided to attempt a repair on it, rather than pay loadsa money for a new one.
After carefully reading the fact sheets, I decided to try to remove the black plastic surround - what I did was to just insert a small screwdriver around the gap - and break the sides off!!
This actually worked very well - it didn't look pretty - but it revealed that two contacts had become unsoldered - due I'm sure to the fan getting stiff due to water ingress.
It appears the thin resistor strips will naturally spring away from the contacts when overloaded - so, after resoldering them, I just applied plenty of Araldite around the connections - figuring that if the same happens again, the glue will prevent the contacts from springing apart again!!
This repair was a great success - thanks to all the previous posts on the subject - I wouldn't fancy being the first one to attempt this repair!!
Result - a fully working fan again.
Well chuffed!!
Mike
