I took him at his word (mistake !) and after Christmas ordered another, and have now tested that and the internal resistance is 3.96kohms, not much better than the fist one and nowhere near correct to give accurate readings, it reads about 38w instead of 60w.!
Now to decide whether to bite the bullet and order a genuine unit to get this unit into use and put these two in the junk box for use in some future project, or whether to go through a recalibration of the scales.
Note to self, avoid anything with SVC on the dial :-(