Hello Mike, and welcome to the forum.
The resistive values you have reported are fine.
As you are probably aware The Mk1 fanmaster was replaced in the later 1990's with the all in one gas and electric heaters. At the turn of the century Carver sold its caravan leisure business interests to Truma, and quite rapidly they removed Carver's products from the market where they were in competition to their own, so the Mk1 fanmaster was never supported by them, and parts will be difficult to find.
However if you contact Gary at
you might find he has some, or has found suitable alternatives.
By the way happy "new year"